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Get Out Your Number 2's!
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'Tis the time of the year that our poor public school children are subjected to those dreaded California State Tests. To help us all feel their pain, if only for a few minutes, I'd like to subject you to some questions similar to those that are plaguing our children during these weeks. They are all astronomy related, so regular readers here should find all this easy like Sunday morning. Got your Number 2 pencils sharpened and ready?
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!
Posted by Mark Ritter at 2008.05.18 10:38 AM | Comments (0)
