Stuff In The Sky

Since the objects in the heavens refuse to stop moving around, this section of my Web site is likely to be updated more frequently than others. I hope to update my Mir predictions every week, and to post information about other interesting things as their orbits dictate.

Note: Unless otherwise indicated, all of the pictures and movies on this page were generated using Sienna Software's "Starry Night Deluxe" program. To see the movies directly in your browser, you may need to download the QuickTime plugin.

The Russian space station Mir can easily be seen with the naked eye from nearly anywhere on earth, if you know when and where to look. Visit my Mir page to see sky charts of upcoming sightings from selected cities (and links to more info, in case your city isn't "selected.")

pthfndr.mov (545 kb)

Ever wonder how you send a probe from the earth to Mars? Simple--you just shoot it into orbit around the sun. This will all make sense to you when you watch this QuickTime movie which shows the motions of Earth, Mars and the Mars Pathfinder, from the day the Pathfinder was launched (December 5, 1996) to the day it landed on Mars (July 4, 1997). Or, you may just want to take a look at a still snapshot from the movie. Also featured in this movie are Mercury, Venus and comet Hale-Bopp zipping around the sun.

For more Pathfinder info and pictures than you can possibly fit into your brain, visit JPL's Mars Pathfinder website.

earthdance.mov (749 kb)

If you sit in the middle of the Sea of Tranquility on the moon, you'll see an Earth that never rises nor sets. That's because the moon moves in such a way that the Sea of Tranquility (and its entire hemisphere) always faces the earth. Always. When I was a young boy, nobody even had a clue what the other side of the moon looked like.

So if you set up camp on the moon's "near" side, and watch the Earth hanging there in the sky, does it hang in exactly the same spot all the time?

Well, not quite, as it turns out. It may never rise nor set, but it wanders around; this is because the moon's speed is not constant as it orbits us, and because its axis is tipped relative to its orbital plane. That makes the moon look wobbly as seen from the earth, and makes the earth dance around as seen from the moon.

But hey, don't take my word for it! Just take a look at this QuickTime movie, which tracks the earth's dizzy path through the lunar sky over a period of 110 days. Or, if you prefer, look at this still snapshot from the movie (which downloads quicker but is not as much fun!)

wobble.mov (900 kb)

Did you know that the moon doesn't really orbit the earth? It's more accurate to say that the earth and moon both orbit around their mutual center of gravity, which is actually a few thousand miles out from the earth's center. Thus the moon makes the earth wobble quite a bit, over the course of a month. This QuickTime movie shows a simulation of this motion, as seen from a point far above (below?) the South Pole.

Click this picture to see a bigger image

An annular solar eclipse occurs when the moon passes directly in front of the sun, but is too small to cover it up completely (the moon's apparent size varies throughout the month, because its distance from the earth varies). The result looks like a "ring of fire" in the sky (the word "annular" means "ring-like"). This spectacular ocean sunset photo was taken by a friend of mine during the annular eclipse of January 4, 1992. It was taken near San Diego, California, which by chance was the only spot of land in the world (other than a few tiny South Pacific islands) from which the ring was visible.