Thursday, October 27, 2005

Here's Mars!

Have you noticed a bright orange "star" in the east after dark? It's hard to miss, so go look for it. This "star" is by far the brightest thing in the east. But this is no star, it is the planet Mars. On Saturday, Mars will make it's closest approach to Earth in over two years, and it will be another 13 years until Mars is this close to Earth, "only" 43 million miles away. Here's a Halloween experiment to help you imagine this scale. Start with the pumpkin on your doorstep. That represents the sun. On this scale, the Earth is a pea located about 150 feet away. Mars would be a half pea located another 70 feet away from the Earth.

So why will it be another 15 years until Mars is this close to Earth, if it were this close just two years ago? This online simulator shows the position of the Earth and Mars as both planets orbit the sun. It takes the Earth one year to orbit the sun, and it takes Mars almost 2 years to finish an orbit. So, the Earth passes Mars about every two years.

But Mars's orbit around the sun isn't a perfect circle. At its closest approach to the sun, Mars is 130 million miles (206 million km) away from the sun, and at its furthest, Mars is 156 million miles (249 million km) away. So, sometimes when the Earth passes Mars, Mars is close to the sun, and therefore closer to the Earth. At other times, Mars is further from the sun (and further from the Earth).

Two years ago, the Earth passed Mars just as Mars was at its nearest point to the sun, and Mars was closer to the Earth (only 35 million miles away) than it had been in 50,000 years! This year, Mars is a little further away from the sun, and so further from us. Again, watch the little simulation I linked to above.

So, how would the Earth look from Mars right now? Would it be a bright blue dot in the sky? Would you be able to see continents with a telescope? No. Although the Earth is close to Mars, we almost directly between Mars and the sun. The Earth would be too close to the sun to see safely! And, even if you could look safely at the Earth, you'd be looking at the Earth's night side, and it would be dark!

Would you like a chance to see Mars through a telescope? Over the next few weeks, your local astronomy club will certainly be having some sort of "Mars party." They always welcome newcomers to look through their telescopes at the Red Planet! You can find the astronomy club nearest to you from this Sky & Telescope directory. Don't wait! In a few more weeks, the best views will be gone for 15 years (though we'll get another, less favorable view in two years).

Want to see pictures taken through telescopes in the last few days? Look here!

No comments:

Post a Comment