What's Up for January? Earth's sister planet, Venus!
Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion
Laboratory in Pasadena, California.
Each month during 2009 we'll be celebrating International Year of Astronomy. We’ll focus on night sky wonders you can see, related NASA missions, and space science discoveries.
Venus is easy to see this month.
Just step outside just after sunset any winter evening. The planet will brighten and appear crescent shaped as the winter months march towards spring.
Venus is sometimes called Earth's sister planet because it's the nearest planet to Earth and it's nearly the same size. But unlike Earth, Venus is obscured by a blanket of dense carbon dioxide. Venus also has several layers of dense clouds composed of sulfuric acid. These clouds completely obscure our view of the planets surface.
Venus has been easily observed for thousands of years, but it wasn't until the 17th Century that telescopes first revealed some of its wonders.
Four hundred years ago, Galileo first observed the phases of Venus through a telescope. The prevailing belief was that the sun and planets revolved around the Earth. The phases looked similar to what he saw on Earth’s Moon each month.
This was evidence that Venus orbited the Sun, not the Earth.
Other observers also sketched the phases of Venus through their telescopes.
You can see the phases of Venus for yourself.
Through binoculars or a telescope, Venus appears as a waning crescent in January and by March you'll see it as a larger but very slender crescent.
Earthly observers have been enjoying views of Venus for centuries. In 1962, Mariner 2 became the first successful mission to visit Venus. Since then, there have been more than a dozen orbiters and landers to visit Venus.
You can read more about Venus Revealed on NASA's IYA website http://astronomy2009.nasa.gov
And you can learn all about NASA's missions at www.nasa.gov
That's all for this month.
I'm Jane Houston Jones.