Quiz Time! The following statements are true or false. Ready?

1. It’s easy to spot Mars in the sky. It’s the only red thing up there!

Mars is known as The Red Planet. And as we’ve seen from all those pictures coming in from those tiny spacecraft traveling about the planet, it does indeed take on a reddish hue. A lot of the surface of Mars is made up of oxides of iron, similar to rust. Hence the ruddy look.

But it isn’t really too red in the sky. In fact, it barely makes pink. But it has enough of a tinge of red that we can still call it the red Planet and not lose sleep about it.

But it’s not the only red thing in the sky. Stars can be red, too! It all depends on their temperatures.

In astronomy really hot stars bleed all the wavelengths of light but really pour out the blue, cooler stars appear white and yellow (like our own), and the coolest stars only get to red.

It’s the small stars, the runts of the cosmic family, that can’t raise their surface temps too high. They can’t fuse a lot of material down in their cores and therefore never really cough up enough energy to heat the place up too much.

But there are monstrously big stars that are red, too. How’s that??? The bigger stars, when they reach the end of their lives, expand to enormous sizes. You may remember from school that when gases expand they cool. As these monsters outmonster themselves, their surfaces cool. As they cool they change color, many eventually reaching redness.

There are several of these “red giants” visible in the skies, one of which is Antares in Scorpius. What an amazing coincidence! Antares means anti-Ares, rival of Ares. Ares was the Greek version of the Roman god Mars. Antares is named so because it is often confused with our friend Mars.

So the original statement is false. Mars isn’t really that red, and there are many other things in the sky that are actually redder.

2. It’s only in the last couple centuries that people have known that the world isn’t flat.

There were these people who lived more than 2000 years ago called the ancient Greeks Some of them liked to sit around all day and think… and think… and then think.

Some of these guys thought about this: Why is the shadow of the earth on the moon always round when there is a lunar eclipse. Well, they thought, what always makes a round shadow? Hmmm…

A sphere of course!

There were a lot of other evidences, too. But the point is, they knew earth was round. They even figured out its circumference, the distance around, without even going around the planet.

Most educated people since those ancient times thought the world was spherical. The uneducated folks often thought the world was flat because… well… it sorta looks that way!

But that we just recently discovered the planet is a big ball is a big myth.

3. The Milky Way we see in the sky and the Milky Way galaxy we live in are the same thing.

Throughout the year, but especially during the summer, there appears in a dark unpolluted sky, a band of light called the Milky Way. It is the source of a thousand myths from peoples all over the world.

But it wasn’t until Galileo’s time that it was discovered that that great band was actually a great field of stars. Peering into the belt with a telescope one can see countless tiny stars of all colors.

And it wasn’t until the beginning of the 20th century that it was discovered that there were other galaxies in the universe, distant monstrous collections of billions of stars each! We were just one galaxy of billions!

It turned out that Great Band of light we called the Milky Way was – ahem - us.

How can it be that we can see countless spiral and elliptical and irregularly-shaped galaxies all over the place filled with billions of bright stars each, but we can only dimly see our own?

To view our place in our great spiral of stars imagine wading in a harbor filled with hundreds of boats. Above you is sky, below you is water. It seems the boats are pretty much limited to a band surrounding you.

In space we have a clear view above the spiral and a clear view below, but in the spiral, where we live, there are literally hundreds of billions of stars, like the boats in the harbor.

Well then, since we are drowning in stars, the whole place should be lit up! Well, there are lots of stars to be sure, but there is also a truckload of dust up there. The dust blocks a lot of the light from ever reaching us.

So, to conclude, the Milky Way we see in the sky and the Milky Way galaxy are the same thing – our amazing home.

How did you do this time? Are there questions you would like to see here? Write me with them!

Until next time, clear skies!