First under the glass is a pair of wonders, Mars and Saturn. They are setting in the western skies together after sunset. In fact, at this very moment they are less than two degrees away from each other in the constellation Leo, near the bright star Regulus. If you can, catch them in the darkening dusk, around 8:30, due west, about 25 degrees up.
But that apparent closeness is just an illusion; they are considerably more than just a breath away from each other. Really they are separated by more than 724 million spacious miles, nearly eight times the distance we are from the sun.
What's kind of interesting trivia here is this: Although we see the two next to each other, we are actually seeing Mars earlier than we see Saturn. We aren't seeing them at the same "time." How's that?
Remember that light is finite in speed. It travels at a ripping 186,282 miles a second, but it is not infinitely fast. Using that as a reference, Mars is 18 "light minutes" away from us - it took that long for its reflected light to get to our eyes. But Saturn is another 730 million miles farther out from Mars, more than a 'light hour" more distant.
Bottom line: If a huge comet smacked into both Mars and Saturn at exactly the same time, we would see the explosion on Saturn a full hour after the one we see on Mars. Crazy things can happen in space.
Speaking of giant rocks hitting planets, it is this week that we celebrate the momentous occasion in 1994 when Comet Shoemaker-Levy 9 (SL9) smacked into our other planetary star of the month, Jupiter.
It was back in March 1993 when Carolyn and Gene Shoemaker together with David Levy discovered a kooky comet with the 0.4-meter Schmidt telescope on our own Mt Palomar. It was kooky because it wasn't going around the sun, it was going around Jupiter!
Apparently our Big Brother with its scary big gravity had snatched this comet right out of its normal solar orbit years earlier and claimed it as its own.
Fine with us Earthlings! Jupiter has no doubt been stealing things out of the sky since the beginning, protecting us from incoming - and devastating - invaders bent on terrestrial destruction.
To make matters worse for the little comet, not only had Jupiter trapped it, but it had more recently chewed it up, as well. Coming too close to giant Jupiter, a small, weakly-held-together body like a comet can get broken up by Jupiter's gravity. SL9 got torn up into a couple dozen icy pieces.
But Jupiter wasn't content on merely trapping and then tearing apart the little guy. As a final insult, Jupiter ate it.
That's what happened in July 1994, fourteen years ago this week, starting on the 16th, when the orbit of the star-crossed, broken-up little comet took it too close to Jupiter, and its remnants slammed into the big guy over a period of several days. Bam, bam, bam - one nasty impact after another struck hard, all of which released probably 1000 times the energy of all the nuclear weapons we have on Earth. It was an exciting time, a great week in astronomy.
Jupiter has more than recovered from what was nothing more than a bruise on its massive atmosphere. Take a look up there during the next couple months with a nice backyard telescope and you will see nothing but the parallel weather patterns, the Galilean satellites, and if you're lucky, the great Red Spot.
But the remnants of the only substantial solar system collision we have ever seen will be gone.
Go out this week if you can and catch a glimpse of all three of the most popular planets out there.
Until next time, clear skies!
]]>That would be an eye-opener, eh?
That's what happened 100 years ago on the 30th of June, 1908, over a remote area in Russia's Siberia, specifically near the Podkamennaya Tunguska River. It is an area so remote that few people lived there then, probably fewer on the outside even knew of it.
The Tunguska Event, as it is understatedly known in the scientific community, was real, to be sure. But a real what?
Understand that at the time, in the early 1900's, there were no satellites, phones, worldwide tracking stations, email, texts, and the like. If some monstrous event took place in the middle of Siberia back then, the news would travel slowly, and any response in getting to this forsaken place would be slower.
In fact, it wasn't until the 1920's that a Russian scientist, Leonid Kulik, curious about local accounts of a Brobdingnagian explosion that happened decades before, made some expeditions there.
Although he deduced that the explosion was from a meteorite impact, his findings - and the findings of all the subsequent expeditions there - discovered hundreds of square miles of felled and scorched trees. But there was no impact crater in the middle of the mayhem!
What on earth was this Tunguska Event, a phenomenon that knocked over more than 50 million trees and exploded with a force 1000 times greater than the Hiroshima atomic bomb, but left no crater?
Dunno!
Believe it or not, the jury is still out on this one. The prime suspects are extraterrestrial, as expected. But as to whether it was a comet or asteroid…? Go there and expect a fine argument.
A small comet is suspect because it is so weakly put together that it would be expected to blow to smithereens when impacting our dense atmosphere, unleashing a truckload of energy but leaving in essence nothing but dust and water vapor.
But a comet just tens of meters across would have ripped apart higher in the atmosphere, and the trace chemical evidence found on the ground imply an asteroid, not a comet.
Exactly one hundred years later there is still no consensus as to what it was. But there is plenty of agreement on what these intruders - asteroids or comets - can do when they hit.
The Tunguska beast was just a small impactor traveling at just tens of kilometers per second that fell over an unpopulated area full of nothing but trees and bunnies.
If the Tunguska rock had struck just hours later, Europe would have been in deep do-do.
A blast like that could easily have leveled a populated city like St Petersburg or London and all its inhabitants. Bigger rocks, on the order of hundreds of meters across or even a kilometer or two, can spell doom to entire continents of life.
We should be thankful that although blasts like Tunguska happen about once every several centuries or so, that most of our planet is still pretty much uninhabited. Nevertheless, a pinpoint strike can kill - big time. Just a little heads up!
Until next time, clear - and safe - skies!
]]>Many of us look forward to the nighttime skies above our heads, and all the glories of the summer heavens.
Sadly, the summer skies come late and leave early. Our tilt, now fully towards the sun, means that it will not get dark until after nine, a late start for many.
But the summer skies are worth it. Let's look a little closer at some things you may want to try and see.
The most obvious summer addition is the summer Milky Way. It's a beauty. Of course how much it inspires pretty much depends on dark skies, a phenomenon going the way of cheap oil. The Milky Way is visible sometime during the night all year long, but what makes the Summer version so pretty is that we are now facing the civic center of our galaxy.
In that direction stars are more concentrated, there are more nebulae and clusters, and there is our dense center. The diamonds-over-the-head view, the one that extends from south to north, doesn't really kick in at reasonable hours until later in the summer. But if you stay up until after midnight, you can see it now.
If you haven't yet, why not try and make this the summer you see nebulae and star clusters. Nebulae are huge luminous gas clouds where stars are being created. Clusters, open are globular, are exactly what they say - clusters of star, sometimes hundreds of thousands strong. There are many located in the southern skies, near the center of the Milky Way.
Alas, Saturn is in its last weeks of visibility, but Jupiter always puts on a fine show. It won't be until July that Jupiter makes a reasonable, pre-midnight showing. But it is worth getting out an old scope to take a look at the big guy, with his striped atmosphere, great red spot, and Galilean Satellites.
You will notice that since we are tipped so much toward the sun, that we end up being tipped away from our nighttime neighbors. So the planets and the Moon won't exactly be hovering over our heads where they are best seen. That's part of the compromise observers make all the time.
In August, specifically around the 12th, we will get our annual Perseid meteor shower. The Moon may mess things up a bit until the predawn hours when it goes below horizon, and which is the best time to see these critters anyways. This year the west coast seems favored to get the best show so it may be worth waking up early to go see these fireballs.
There are all kinds of wonderful things to explore in the summer skies, and the fact that the weather is usually nice here in Southern California helps a lot. I would suggest getting a recent copy of Sky & telescope or Astronomy magazines if you are seriously considering checking out the skies. They have detailed and easy-to-read sky charts in there for nailing down those clusters and clouds and planets. It would be a fine season maybe just to spend the time relaxing and try to "de-stress" by getting a map, some binoculars, a lounge chair - and just looking up. The effects are amazing.
]]>It really is an amazing feat getting that little guy to a target 100 million miles away and safely landing it. But now I fear I risk sounding like the Grinch Who Stole Christmas. Why?
For those of us who read, eat, and drink space, we have listened to plenty of people over the years who spend their waking lives looking for life outside our planet. A noble cause to be sure, but if one listens to what is being said - I mean truly listens with slightly skeptical ears - there are some things being said which beg further examination and which tie into our latest Martian encounter.
Invariably a comment is made that goes something like this: To find life, follow the water. True, any kind of life, even the most simple, with its endless complexities, demands the universal solvent we call water. It is an amazing molecule worthy of several articles devoted entirely to its awe-inspiring characteristics.
So to look for water in the universe in hopes of finding life is sensible. Where we venture into nonsense is to make the implication that where water is there must also be life. As if water plus rock guarantees life. "Well, it happened here, so it must have happened elsewhere." Oh, must it have? Well, out comes my skeptical Scroogie science self who then asks, Why "must" life pop from nonlife with nothing else but rocks, water, and time?
Maybe we have heard the "If there's water there's probably life!" mantra so much over the years that we have become numb to it and don't critically think about it. But, as one trained in the sciences to eye all things with a healthy skepticism, I might ask: If life pops up so easily, how does it do so? If it is so ubiquitous, why can't we make it pop up in the lab? Why should we expect blind, random, mindless nature to "just do it" all over the universe?
Which often brings up the inevitable theological statement: If God is the source of life then He can put life wherever He wants! That is absolutely true. But my questions are directed to those who claim no invisible means of support, to those who claim that nature is all there ever has been, all there is, and all there ever will be, to paraphrase the late Carl Sagan.
The Phoenix, a remarkable little lab in its own right, may find signs of ancient water. That would provide us with marvelous insight into the history of our solar system. It would afford more evidence that either supports or breaks down countless hypotheses floating about concerning Mar's past. That in itself is a great stride for planetary science, and to that my hat is off.
But allow me a humble prediction concerning Phoenix. Everywhere we look in the universe - I mean everywhere - we pick up more and more evidence every year that we are one of a kind, this planet of ours. Earthlike planets are not a dime a dozen as once thought. Our makeup is extraordinarily and exquisitely perfect for life. I believe that Phoenix will not make a case for ancient life on Mars. On the contrary, I believe it will provide even more evidence that our planet is even more extraordinary than we now believe it is.
Might I be wrong? Of course! That is part of the beautiful discipline of science. But part of science also involves evidence and models, two things sorely lacking in the "life must be everywhere" scenario.
I hope all this starts some good discussion. Are we unique or is life everywhere, including Mars? Is there life because of a long random set of mindless events, or did Someone put it here? Why is there Life at all?
Maybe like its mythical namesake, the Phoenix spacecraft will bring to life from the ashes the Big Questions that we seem to have forgotten to ask anymore in our busy, busy lives.
Until next time, clear skies - and clear thinking.
]]>Question 1: Which sequence correctly lists the relative sizes from smallest to largest? (A) solar system, universe, Milky Way Galaxy, (B) solar system, Milky Way Galaxy, universe, (C) Milky Way Galaxy, solar system, universe, (D) Milky Way Galaxy, universe, solar system.
Most if us know the solar system is the smallest of the triad, which, in good test taking practice, eliminates (C) and (D) and narrows it to (A) or (B). But many people are not too sure of what's next in size. Both are huge, but one is huger – more than 275,000 times huger.
The Milky Way, our home galaxy, is generally believed to be about 100,000 light years across. The visible universe is more than 13 billion light years in all directions! And that is just the visible universe; the actual size may be much greater. Correct answer: A resounding (B).
Question 2: Stars begin their life cycle in (A) a black hole, (B) a nova, (C) a nebula, (D) star eggs.
Star eggs? What the…? No, not star eggs. A black hole is how some stars end their lives, not begin it. A nova is how some other stars sputter out towards the end, and although we have rarely talked here before about novae, there is no need to know about one to eliminate it as an answer. Remember the Orion Nebula? It is there that countless baby stars are presently being born. Nebulae, you may recall, are the celestial clouds that can condense down to form new stars. Correct answer: (C)
Question 3: The seasons of Spring, Summer, Winter, and Fall are a direct result of which phenomenon? (A) Earth's proximity to the sun, (B) shifting ocean currents, (C) the 23.5 ° tilt of the Earth, (D) global warming.
Global warming? Uh… no. But you would not believe how many students, even graduates from university, answer with some variation of (A). In their defense, it does seem almost self-evident: Close to the sun implies hotter, thus summer, farther means colder, thus winter. But then how do people in the southern hemisphere celebrate just the opposite seasons as we? Why, when it is summer here, is it winter Down Under?
If you have been even the casual reader here over the last decade you know that one point that has been pressed home is that our seasons are due to our perfect tilt. Our tilt with respect to the sun allows us to get more solar exposure during part of the year, and less six months later. Tilted towards = summer. Tilted away = winter. Spring and Autumn are the in-between points. And you may also remember that our Earth tilted any more or any less results in global misery. That magical 23.5 is our very special tilt angle. Correct answer (C).
Question 4: The highest tides are due to (A) sun and moon working together, (B) sun and moon working against each other, (C) the moon only! (D) global warming.
Well, despite the fact that global warming is now The Hot Topic (pun intended), it is not the catch-all answer to every earthly phenomenon. Many of us know the moon plays a role in the tides. But did you know the sun plays a role as well? Its gravity also tries to yank the water off this planet, but with a little less strength than that gift of a nearby satellite we call the moon.\
And when they act together, as when they are on the same side of the Earth (or opposite), the tides are extra high. We call that spring tide. They work against each other when at right angles to each other, like the 12 and 3 positions on a clock with us at center. That resulting not-so-high tide is called neap tide. Correct answer: (A).
How did you do? If you are a regular here, or just love the subject, you probably aced it. If not, fear not! There is always time to get yourself educated in the best of scientific disciplines on or off this planet, to wit, astronomy.
Until next time, clear skies!
]]>Saturn happens to be parked in Leo this year, although we might more accurately call it a rolling stop. The giant ringed planet is traveling very slowly through Leo taking its sweet time to get to Virgo. But because it is so far away - and the laws of planetary motion tell us that the farther away you are from your star the longer it takes to get around it - Saturn will be in Leo until August 2009. Saturn is no Mercury.
But it would be a good thing to see Saturn this year, not next. The next time we come around to its side of the neighborhood, about a year from now, it will not be the Saturn we all know and love. The rings will almost seem to have disappeared.
You see, Saturn has a tilt like we do. By next year the planet will be at that point in its orbit where its position from our point of view will give its rings almost no tilt at all. And the rings are paper thin (actually only tens of meters thick). Bad news for ring junkies. Imagine someone down the street tilting a piece of paper so it is edge-on with your line of sight. Voila! The paper seems to vanish.
And Saturn without its rings is like a lion without its mane. It's not much more than a giant, featureless ball. That ranks low on the Exciting Things To See In The Sky scale.
But it will still have that one bizarre quality that planets possess. It will not twinkle. Yet the stars around it, like bright Regulus right next to it, will. Why?
It has to do with distance, and that annoying outer layer of our planet called the atmosphere.
Regulus is "ginormous," as my young son might say. It is a star over 4 times bigger than our sun. Imagine a sun the size of that sucker in our skies. But it is 78 light years - over 458 trillion miles - away.
Now in your mind"s eye, take Regulus from where our sun is and move it farther and farther and farther away. It shrinks and dims, and shrinks some more. By the time Regulus gets to its actual position in the galaxy, its size in the sky goes almost to a true point. And that, my friends, is the key.
The miniscule shaft of life that hits your eye from that distant star is unimaginably small and subject to even the slightest changes. What changes? Changes it encounters as it hits our atmosphere. It is then that the poor shaft hits our wall of air, air filled with countless pockets of different temperatures.
These different temperatures cause the tiny shaft to change direction every so slightly, but enough so that by the time it hits you the shifting shaft of light makes the star appear to jump around or twinkle.
But Saturn and the rest of the planets don't twinkle. Why? Now you have the tools to figure that out.
The planets, although very much smaller than stars in size, are not nearly as far away. They do not reduce in apparent size down to points of light. They still have a visible disk.
And yes, the atmosphere messes up their light paths, as well. But instead of one little shaft of light slapping you in the eye, here we have light from all parts of the planet's disk firing away at you – from its top, bottom, middle, and sides. They all get bent out of shape as they race through our atmosphere, but all the planet's flood of light more than compensates for any wayward photons that might get bent out of the way of your eye. Overall effect: No twinkling.
Is there anything you would be interested in reading about here? Any burning questions? Let me know.
Until next time, clear skies!
]]>But some may question the presence of a new mark on the lion, just at the bottom of the question mark, a mere finger width left from the bright bottom star. The stranger is bright enough to disrupt the familiarity of what we normally see there. It is no new star, but the planet Saturn, right there above our heads in all its golden glory.
Of course I would encourage you to take a look at the Ringed One in the next weeks. It is always a crowd-pleaser no matter how many times you look at it.
But I thought this might be a good opportunity to toss in a brief look into the relative brightnesses of heavenly objects.
First, if you go out tonight and take a look, you will notice the brightest star in Leo's big question mark is that same one right next to Saturn. That is Regulus. It is a monster star, more than four times bigger than our own sun. And it pours out over 200 times the energy of our star.
It is an impressively big star, to be sure, yet it is dimmer than Saturn, a mere planet in our solar system that pours out essentially nothing as far as energy is concerned. On a brightness scale we say Regulus has an "apparent magnitude" of about 1.3. Saturn's apparent magnitude is about 0.5, which, in the crazy world of magnitudes, makes it nearly twice as bright as Regulus.
So why is Regulus dimmer than Saturn if it is so much more violent and inherently bright? The obvious answer is that it is farther away - obvious maybe, but in astronomy critical as well.
Regulus is about 78 light years away. This is not a great distance in a universe that is over 13 billion light years in all directions. But it is, nevertheless, about 480 trillion miles away. Take a star that far and even the big ones can get pretty small and dim pretty quickly.
This distance dimming thing is an essential tool in astronomy for this reason: If we know how bright a star should be, and we look up and see how bright it appears to our eyes, we can estimate how far away it is.
Here's an analogy. You know how much light pours out of a 100-watt light bulb at arm's length. If your friend were holding that lit 100-watt bulb somewhere down the street, we could use some simple instruments to measure how bright it appears to be, and with some uncomplicated math, we can then estimate how far away he would have to be for the bulb to be only that bright. We are using brightness to estimate distance.
That is a wonderful tool in a discipline where it is impossible to stretch out tape measures even hundreds of miles, let alone hundreds of trillions.
Saturn is brighter because it is so very close to us, just over 72 light minutes away, about 800 million miles. But even though it is next door, it is not all that bright because, as is true for all planets, it does not give off its own light, but reflects the light of the sun.
Next time here we will continue to look at Saturn and Regulus and see why one twinkles and the other does not - distance plays another starring role - and why it is sort of important to see Saturn this year and not procrastinate until next.
Until next time, clear skies!
It was there that a special satellite named Swift noticed just the faintest flash of light. But what a flash of light! If you had been out in the darkness away from the city lights and looked exactly in the right place at exactly the right time you too would have seen it - just barely.
How exciting, huh?! No? Well, actually it was! Let me tell you some more of the facts and then maybe you will feel sorry that you, too, weren't able to witness this extraordinary event.
Once astronomers got a quick bead on this transient flash, they were able to conclude that it was an elusive gamma ray burst (GRB). These phenomena are the most energetic group of explosions we know about, even bigger than the heavens' conventional weapon, the supernova. There are several possible models for what these critters might be, but the latest ideas make them out to be superduper supernovae.
The more common supernovae we've all heard about are the explosive deaths of stars. They go kaboom, we go "wow," life goes on.
But these gamma ray bursts seem to be supernovae on steroids, focusing all their explosive power and energy out two narrow poles instead of all over the place. If we happen to be in the sights of one of the poleblasts we get a face full of energy right before our face vaporizes. And there is enough energy in those bursts to wipe out life on earth if one of them occurs in our galaxy and is aimed our way.
Now back to our Big Blast from a couple weeks ago and why it was so astonishingly colossal.
When astronomers looked at the data, they discovered that this particular GRB was a ways away. Not thousands of light years away, not millions, but billions of light years away. About 7.5 billion to be precise.
To put things in a time perspective, this means the star went blooey billions of years before our own star and its planets (including Earth) were even born. And its light just reached us now.
To put things in an energy perspective, let's use our star for comparison. You can imagine that if we moved our blindingly bright sun farther away from us it would get dimmer. Move it about 40 light years away and it would be so dim we couldn't see it naked eye. That's just 40 little baby light years, about 240 trillion miles.
And yet we could see this bad boy from 7.5 billion light years away. Imagine how incredibly bright it had to be to be seen halfway across the known universe!
This is what amazed astronomers - but not many other humans - when GRB 080319B appeared in our skies. The amount of energy needed to be that bright from that far away was more than 2 million times greater than the already mind-numbing amount of energy from the brightest recorded supernova. That is inconceivable.
This is why astronomers, professional and amateur, would have been in heaven just to catch a faint glimpse of the light with their own eyes. It was an historical moment in the Realm of Astronomy.
But alas! That GRB is dead and gone. All we can hope for is another big one. But, please, not too big or too close, too energetic or too focused. We would like to live to tell the tale.
Until next time, clear skies!
]]>Actually what you are looking at are their big, bright, hot heads. Castor’s is the bluer one, Pollux's star is a wee pinkish. Their skin-and-bones bodies trail off to the west making the starry duo's constellation appear, in toto, as a rectangle in the sky.
Their story is a typical ancient myth, filled with naughtiness and violence and escapade. One genesis of the Gemini goes something like this: There once was a princess named Leda who was of exceeding beauty. The big god of Olympus, Zeus, saw her beauty and to no one's surprise wanted her real bad. On her wedding night, when her husband was temporarily away, Zeus showed up disguised as a swan (don’t ask) and had his adulterous way with her. Her husband later consummated the marriage after Zeus flew the coop.
This was awkward to say the least, but the result was even more bizarre. She conceived two pairs of twins in a single, apparently very roomy egg. The one pair was immortal because of Zeus' contribution, the other pair mortal.
The boy from the immortal pair of twins was Pollux. Castor was his mortal half brother twin from the mortal side of the egg. The other kids apparently fell into relative anonymity.
The brothers ended up being as close as... well... brothers and shared a full life of boxing and soldiering and general horsing around. One of their fun times together included saving the Argo fleet from one nasty storm. This endeared them to sailors for centuries, and mariners would carve their likenesses into the bows of their ships for protection.
In their last caper together Castor got himself killed, much to the anguish and anger of both Pollux and Zeus. They dealt viciously with his attackers. Zeus afterwards saw that Pollux was deeply distraught and told him to come on up to Olympus. Pollux could get through the Olympic bouncers because his dad was Numero Uno. Castor, however, a mere mortal, was sent to the underworld. Well, this didn't sit well with Pollux – being a way from his brother – and he wheeled and dealed with Zeus until they worked out an agreement where the twins would spend alternating days above in Olympus and below in Hades.
In a poetic way we see that brotherhood in the skies today. Pollux descends below the western horizon almost immediately after Castor, and when they rise in the evening, there is Castor with his good brother Pollux right on his heels.
To astronomers these two stars have a real life of their own, but they are not twins, to be sure. Pollux is an older, redder, giant star, the brighter of the two. It is a lone star but just last year it was confirmed that there was a Jupiter-type planet in its grip.
Castor is another story altogether. Appearing as a single star to our eyeballs, it is "split" into a double star with any backyard telescope. It would be a nice play on the myth if it were just a twin binary, but observing the two with special instruments, it turns out each of those stars is itself a double star. These two sets of twins would be another nice lyrical ending to this sky story but there’s more!
It turns out there is a third, fainter star gravitationally bound to the first two sets of twins, and that that star itself has a twin, too. Sheesh!
That makes the Castor system a triple double system – six stars gravitationally bound, taking anywhere from days to centuries to go around each other in their heavenly dance. Twins everywhere!
Castor and Pollux are easy to spot, but if you cannot see them go out on the evening of April 12th when they and the first quarter Moon line up nicely like, well, triplets!
Until next time, clear skies!
]]>Where were Uranus, Neptune, tiny Pluto and all those freakish things we have been learning about here over the years – galaxies, pulsars, quasars?
Their existence, in the eyes of humankind, was not known until the advent of a tiny tool we call the telescope, a tool that allowed us to spot these anomalies heretofore undetected by mere naked eye observation.
It was 227 years ago this week that the famed astronomer William Herschel, using a homemade telescope, doubled the distance to the borders of our solar system, extending it outward over another billion kilometers beyond Saturn. It was he who discovered Uranus, the seventh planet.
Usually I tell you where in the sky you can find the featured object. Sadly, Uranus at the moment is on the opposite side of the sun. That means it is now up only during the day, right next to our blazing star. To avoid a lawsuit I would recommend not looking for it. The resulting blindness would prevent you from finding it later this year when it claims the night skies once more.
As to its discoverer: William Frederick Herschel was born in Germany but in his teens took up residence in England. He, like many well-off gentlemen of his time, had a penchant for dabbling into the different disciplines. He was, for example, an accomplished musician. It was that an art that led him into the land of mathematics.
It was through math that he discovered the amazing world of astronomy. During this time, in his mid-thirties now, Herschel began constructing his first telescopes. He would end up making over 400 in his busy life.
When he was 43 years old, living in Bath, England, he discovered with his own telescope what he thought at first was a comet, but which shortly thereafter was shown to be a seventh planet, the first planet discovered since man was put here.
It had actually been seen before by other astronomers but was mistaken for a star. Herschel noticed in a series of observations that it moved just slightly, hence the initial thought that it might be a comet. But it turned out to be a far more distant heavenly body, a new planet.
Being a loyal Brit now, he named his newfound planet after his king, George III. Yes, the same George who gave the colonies in America so much grief.
Now, let's see how that new planet line-up might sound if the name had stuck: Mercury, Venus, Earth, Mars, Jupiter, Saturn, George. Hmmmm...
It was proposed by another astronomer that the planet should be named Herschel in his honor. Ahem. Thankfully, wiser, more traditional, minds prevailed, and the planet was named for the Greek god of the sky, Ouranos. Despite being more traditional, even that name broke ranks with the other planet names, being a Greek deity rather than a Roman one.
By the way, astronomers prefer to pronounce the planet's name with emphasis on the first syllable, not the second. It is not only preferred but can keep giggling to a minimum when you pronounce it in front of high schoolers. Trust me.
Herschel went on to do a lot more work in his life. He showed that gravity worked outside our solar system by keeping binary stars together. He built all those scopes, of course, some monstrous. He did some amazing studies with the Sun. And he would discover new moons around Saturn and George... uh... Uranus.
And he left behind a legacy, as his son John carried on the family tradition and became a famous astronomer himself.
But there was at least one more planet to be discovered! Alas, that’s a story for another day.
Until next time, clear skies!
]]>It was actually discovered the summer before, in July 1967, by a young postgraduate student at Cambridge, Jocelyn Bell. And as is common in the sciences it was discovered without being looked for. She and her thesis advisor had been doing radio astronomy on far more distance objects when out of nowhere popped this little throbbing goblin.
Radio astronomy uses the radio part of the electromagnetic spectrum to "see" things out there, things invisible to our eyes. While searching deep space with her radio telescope she came across a strange pulsing of radio waves coming from an unknown point in space. Like a heartbeat it was very regular, unlike a radio noise one might expect.
It was such a regular pulse that it was suggested the signals might have been from an intelligent source, perhaps an alien civilization. Tongue firmly in cheek, the strange discovery was first called LGM-1, for Little Green Men.
The humor aside, the object was a mystery. But shortly after the release of the paper, astronomers figured out what it was. It turned out that the pulsar was just another stellar object we already knew about, only seen from a different point of view. It was a neutron star. But what is that exactly, and why do some pulse?
A neutron star is the core remnant of a giant star that went boom. When a massive star dies, it blows away its outer layers in a giant explosion called a supernova. But the core implodes into a superdense ball of neutrons.
When I say superdense, I mean superdense. A cubic inch of this stuff would weigh in at 100's of millions of tons. That, my friends, is superdense!
Moreover, when one forms it spins just like the star it came from, but it spins fast. You guessed it... superfast. Like an ice skater bringing in her arms to spin faster, the neutron star, shrunk to the size of a large city, can spin fast - hundreds of times a second.
This high spun neutron star has a north pole and a south pole, the result of an intense magnetic field. It is out of these poles that radio waves spew.
This all leads us back finally to the pulsar. You might already be able to figure out what those pulses are. If the neutron star is spinning like a top but the magnetic field is slightly off axis, you can see how its radio beams could sweep out an area like the searchlights at a world premiere.
I'll use the classic lighthouse analogy as an illustration. As the beam of light from a lighthouse sweeps around and around, those on the horizon – in the line of sight – see what appears to be a regular pulse of light.
That is what a pulsar is like. It is a neutron star whose expelled radio blast is in our line of sight. We see the "pulse" each time it sweeps by. Other neutron stars could no doubt be pulsars if they would just line themselves up with us.
Once they were found, astronomers went looking for them and found them by the bucketsful.
As to Jocelyn Bell, her faculty advisor got a Nobel Prize for his work in pulsars. Jocelyn was passed over. Hmm... At any rate, her discovery of the pulsar has probably inspired many young women to take up a discipline long held captive by men. Someone say "Amen!"
Who needs a Nobel Prize, anyway.
Until next time, clear skies!
]]>The timing of this particular eclipse is perfect for those of us in southern California, and we won't get it this good again for a couple years. We essentially get to see the whole show at a reasonable hour. Now we may miss part of the first act, but that's OK; the opening act is a snoozer. Here is a synopsis of our play.
Every month the Moon makes one trip around our planet. During that circuit it manages to get itself on the side of the earth opposite the sun. When it does this it risks going through our huge shadow. Because the Moon's orbit is slightly tilted, it doesn't always manage to hit the shadow, but it will on the 20th, and thus we have ourselves an eclipse.
The whole process takes several hours, which will give you some time not only to relax and enjoy it, but some time also to observe some other cool science things.
When the moon first peeks over the eastern horizon, it will already be fully into what is called the earth's "penumbra." The penumbra is just the partial shadow an object lays down. You have unwittingly experienced it yourself. As the sun rises in the morning from behind a distant hill or mountain, we do not see the whole sun yet. When it first shows itself, when all we see is part of it, we are in the partial shadow - the penumbra - of the earth. The sun is neither completely hidden from us, nor is it blazing in all its full glory.
This is what the Moon is experiencing when an eclipse begins. For someone on the Moon, the sun appears to be moving behind the earth. But a penumbra is still so bright, most of us would never notice it.
It isn't until the Moon moves completely into the full shadow, the umbra, that the show really gets underway. This will have just begun as we see the Moon rising Wednesday. You will see it maybe a third covered in the dark umbral shadow.
Notice at this time, too, after the sun sets, how the whole eastern horizon seems to be lifting up in a purple haze. That curved semi-darkness is the earth's shadow, the same shadow the Moon is moving into.
Over the next hour or so, until about 7, watch how the shadow crosses the face of the Moon, darkening it. Notice also how the shape of the shadow is curved. It is always curved. This fact led ancient Greeks to believe the earth was a sphere, the only shape that always has a curved shadow.
The darkness will last for about an hour, it takes that long for it to pass through. It is at this time you might notice that the Moon takes on a reddish appearance. That would be because our own atmosphere bends the light from the sun, like a lens, toward the Moon. The only wavelengths from the sun long enough to make it through all our atmosphere and get the free trip to our satellite are from the red end of the spectrum. More poetically, all the world's sunsets are bleeding towards our Moon.
Just before 8 PM, the Moon will have reached the other side of our shadow. The umbra will begin to give way to the penumbra, all the main action having been completed. By about 9 PM the umbra is gone; by 10 PM the nearly invisible penumbra will fade by and the entire show is over.
This will be the last time to see a total lunar eclipse at a reasonable hour for a couple years. You and your family, or school class, or scout troupe might want to make it a nice evening of observation of one of the heaven's free dramas.
]]>Which planets have rings? Well, of course we know that Saturn has rings. For hundreds of years it was the only planet with rings. But recently we have discovered that Saturn's neighbors, the so-called gas giants, also have rings. But they are so faint they weren't discovered until a short time ago.
Uranus was the first planet after Saturn to show us its rings, although we first had to pry the fact from it. In the mid-70's astronomers observed that distant stars would flicker just before and after Uranus passed in front of them. The reason must have been faint rings cutting off the starlight. In 1986, the spacecraft Voyager 2 flew by Uranus and sure enough, there were the nearly imperceptible rings.
It turned out Jupiter had them, too. They were discovered in Voyager 1's flyby in 1979. But don't expect to see them with your backyard telescope. They are essentially made of dust. Only the biggest scopes here on Earth can catch a glimpse of them.
Then, not to be left out, Neptune revealed his rings. Suspected to exist by the same flickering of stars as Uranus' rings showed us, Voyager 2 confirmed them in 1989. It appears that all the big guys - not just Saturn - wear rings.
What is the hottest planet? Most would suspect, intuitively, that the planet closest to the Sun would be the hottest, to wit, tiny Mercury. And Mercury is hot, to be sure - very hot. At its equator it can get to 800 degrees Fahrenheit.
But even as hot as that little guy is, it isn't the winner. Venus is actually hotter - averaging almost 900 degrees Fahrenheit.
But how can a planet more than 50 million kilometers father away from the sun than Mercury be hotter? Because Venus is swaddled in an atmospheric blankie. Poor Mercury has no atmosphere to hold onto the heat, which is why its dark "nighttime" side gets to 300 below.
But Venus has an extremely thick carbon dioxide atmosphere. And carbon dioxide has a notorious ability to hold on to heat; it is the prime suspect in global warming here. This is precisely what is happening on Venus, the warmest planet in the solar system.
How does the sun burn? It was believed since time immemorial that the sun was hot because it was burning stuff, just like fires do here on earth. But if that were what was happening it would have had only tens of thousands of years of stuff to burn, not b-zillions. There had to be another, more efficient way. It took Einstein and his contemporaneous colleagues to figure this one out.
A group of really smart people of his time discovered that the nucleus of an atom stores a wealth of energy, a great wealth, a fortune. It seems that if we rip apart giant nuclei, or smash together very tiny ones, a tremendous amount of energy is liberated.
That is what happens up there in the sun. At its very hot and high-pressure center - the core - tiny little hydrogen nuclei are forged together to form helium. In the process, a prolific amount of energy is released and eventually makes its way to the sun's surface, released now into space.
There is enough hydrogen left at the core for our sun to burn nicely for several billion more years. No need to feed those flames, all is well.
Feel a little more "literate"? Hope so.
Until next time, clear skies!
]]>The probe was named for Christian Huygens, a Dutchman of extraordinary talents. Neither he nor the namesake probe are well known by the general public, but both played an important role in moving us forward in this discipline of astronomy.
Huygens lived in the 17th century, the real kickstart century for the scientific revolution. He was well educated in... well, a lot of things. He studied law and mathematics at first but eventually wandered into physics and astronomy. He dabbled with and invented and engineered two types of instruments that play huge roles in astronomy: clocks and telescopes. He was a man of many hats. In the truest sense of the term, he was an educated person.
More specific to what we are talking about now, it was in the late 1650's that the overactive Huygens developed a better way to grind lenses and with these constructed some wonderful telescopes. He used his refined telescopes to confirm that Saturn's strange and unexplained rings were not appendages growing out the side of Saturn, nor were they one solid disk of material. They were collections of innumerable "rocks" orbiting about the planet.
Moreover, with his scopes he discovered a moon around Saturn, a behemothic moon later christened Titan.
As time went on and telescopes got better, it became clear that Titan was a special satellite. It was more than 1000 miles larger across than our own moon. It is even larger than Mercury. But what set it apart was not just its extra large girth - it was a moon with an atmosphere.
Before we sent the Cassini-Huygens spacecraft there, not much was known of Titan. Its hazy atmosphere prevented scientists from seeing the surface. What was below? Was there just a rocky surface? Were there lakes and oceans of methane as predicted by temperature and pressure data?
When NASA sent the Cassini spacecraft to Saturn in the 1990's they efficiently decided to kill two birds with one stone. On board the massive Cassini spacecraft they would piggyback a smaller bundle of instruments - a bundle with a parachute.
This probe, named Huygens, would be released from Cassini to fall onto Titan, recording the whole journey along the way.
Well, three years ago Huygens fell to its destination and landed on the mystery moon, dropping through the haze and landing successfully on its surface. What Huygens and the Cassini spacecraft flying above discovered was not exactly what planetary scientists were hoping for.
It had long been thought that Titan might be covered in shallow seas of methane and ethane, hydrocarbons which are gases on our planet, but which on bitter cold Titan would be liquid.
Although Huygens snapped some pictures of what seemed to be liquid-worn terrain, the oceans were not to be found. Such is science; sometimes revealing the truth about something can take some the fun out of it.
Huygens also sent back images from the frozen surface itself, and eerie place surrounded in a kind of "sand" made of water ice.
The little trooper of a spaceprobe breathed its last after just an hour and a half on the surface. But Cassini, the mothership that brought Huygens to Titan, is still making the papers, sending back those incredible images of Saturn and snapping pictures of Saturn's moons as it flies by them. Just last week Cassini flew by Titan again, revisiting Huygens' final resting place.
If you can, take a virtual trip to Titan and Saturn at saturn.jpl.nasa.gov, and see the images both spacecraft have sent back. And if you can, grab a telescope this season and discover for yourself both the ringed giant Saturn and tiny Titan next to it, just as a young Christian Huygens did over 350 years ago.
]]>The last year in astronomy was not too too exciting for amateur astronomers. I mean, we didn’t have any local solar eclipses, or devastating supernovae, or spectacular meteor storms. But we did have our planet buddies to keep us company, and several nice comets. They, and the ever present starry firmament, are there every year and always making looking up well worth the effort.
It was a very good year as far as the technological side of astronomy is concerned. We touched down on Titan, Saturn’s largest moon, and saw for the first time its cloud-covered surface. Streams of data are still coming back from spacecraft on or around Mars and Jupiter and Saturn, all giving us unprecedented looks at these ancient planets, all helping us to refine our knowledge of our solar system, a sui generis work of art.
Astronomers also found more planets outside our solar system. Their discoveries bring joy to two groups of people: to one group who exclaims "Lots more planets means lots more chances for life!" and to those who because of the hellish nature of these new planets reason, "There's no place like home... There's no place like home..."
And after a 13-year wait, we saw first signs of life in the world's largest scientific instrument, the Large Hadron Collider in Switzerland. This critter, we hope and pray, when fully operational will be able to simulate conditions in the universe when it was a mere babe, just billionths of a second old.
Now for this coming year, 2008, there will be all kinds of wonderful techie and cosmological stuff revealed and discovered, to be sure. But what can we backyard astronomers do in the meantime, between press releases? Here are some suggestions.
On February 20, at sunset, the full Moon will rise in the east. So what? It will be announcing the opening act of a total lunar eclipse. We in Southern California will be able to watch the whole play unfold over the next several hours. Make sure you see it. We will not have another total lunar eclipse until late 2010!
If you can get a look at Saturn through a telescope this spring, do. Next year will be disappointing. Why? Saturn, like most planets, has a tilt. This year it is still slightly tilted with respect to us, so the rings still are a thing of beauty. But next year we see the glorious rings edge-on and they, in essence, vanish. Boring!
Coincidentally, Saturn will be right next to the Moon during February's eclipse extravaganza.
Here are several things you might want to try this year, as well. One would be to commit to seeing a meteor shower; they are scattered throughout the year. Another might be to see an asteroid, like the great Ceres. Or you can attempt to see all the planets in a calendar year. Perhaps subscribe to an astronomy magazine like Astronomy or Sky and Telescope. Read newspaper articles on the latest cosmological discoveries. Have deep discussions with friends and family about the philosophical and even theological implications of all that is going on in the heavens.
Learning from the past and committing to a future of deeper understanding and appreciation of the cosmos is a win-win situation. It helps us see better our place in the whole wonderful Grand Scheme of Things.
Until next time, clear skies, and a happy 2008!
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