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You Have Queries, We Have Responses
The Solar System >
It's Question and Answer time here this week. Let's get to them!
Q:
I thought Mars was at its closest approach a month ago and it would then
leave the skies. Why do I still see it?
A: Some in the media when they get hold of an event like Mars’ closest approach to Earth in 60,000 years don’t tell us the entire story. Yes, Mars was very, very close to us, and that should be sung from the highest mountaintops. But few stories I read filled us in with the whole caboodle.
We’ve just passed Mars on our inside lane around the sun, hence our closeness. But it doesn’t all happen in the twinkling of an eye. Mars will be in the sky for several more months before we are on the other side of the sun and it goes out of sight.
But it is definitely getting farther and smaller and less fun to look at through a telescope. Today, for example, it is about 41,360,000 miles away. Tomorrow it will be about 41,750,000 miles away - nearly 400,000 miles farther away in one little day. See for yourself in the next weeks how it gets dimmer and dimmer.
And speaking of planets…
Q:
What are those bright lights in the east in the early morning right before
sunrise?
A: Gee, I guess I sort of gave that one away. Those are two of our friendly planet neighbors, Mercury and Jupiter. From about 5.30 to about 6.30 you can see rising before the sun Jupiter – the bright one higher up – and tiny, hard-to-see Mercury. Mercury will head towards the sun in the next week or two. But Jupiter will continue to fill in temporarily for Venus as Morning Star for more than another month. (FYI: Venus is desperately trying to be the Evening Star at the moment.)
And speaking of sunrise…
Q: Is it true that the equinox is when the sun rises due east for everyone and sinks due west?
A: We have just passed the autumnal equinox. This is the moment when our planet is tilted neither toward nor away from the sun. We have light from pole to shining pole. There are several interesting consequences to this.
One is that the time the sun is above horizon is equal to the time it is below.
Another
result is that, yes, the sun rises exactly in the east and sets exactly
in the west. Now, we are just days past equinox so it won’t rise
and set at exactly at the cardinal points, but close enough for you to
do some observations of your own.
If you are up early enough you can mark the point on the horizon where the sun rises; over the water tower on yon hill, or over Old Man Jenkins’ barn, or just to the right of Mrs. Puff’s Driving School. That is due east for your home’s location. (Of course, you can do the same in the evening with the setting sun to find due west.)
But notice in the weeks to follow how the sun rises a little farther to the south each day, and skim over the sky a little lower only to set a little further south in the west. Our position relative to the sun is tilting more and more away; the days are shortening and the weather should be cooling down.
Should be.
If you have any questions, feel free to send me a letter and maybe we can learn together a little more about the beauty of the creation in which we are all blessedly immersed.
Mark Ritter teaches astronomy at Temecula Valley High School and can be reached at mritter@firstlightastro.com.
Posted by Administrator at 2003.09.27 01:09 PM | Comments (0)
