Sagittarius is wrapping up its annual evening appearance. It’s low in the southwest as night falls, and will drop from view over the coming weeks. Some of its stars form the outline of a teapot. As it drops toward the horizon, the spout is tilted down, as if it’s ready to pour its brew onto the ground below.

The constellation can be a little tough to find when it’s this low in the sky, especially through the fading twilight. But it’s pretty easy to find right now because a brilliant visitor is moving across it: Venus, the “evening star.” The planet far outshines every other point of light in the night sky, so you can’t miss it.

Tonight, Venus passes within a whisker of the star Phi Sagittarii, which connects the teapot and the top of the handle. Although the star is billions of years younger than the Sun, it’s already at the end of its “normal” lifetime. It’s moving from the prime of life into its “giant” phase. Changes in its core are puffing up its outer layers. Over the next few million years, that will make the star much bigger and brighter.

On Friday evening, Venus will pass just as close to the star at the corner of the handle. Known as Nunki, it’s the second-brightest member of the teapot. It’s still in the prime of life, but it won’t be for long. It’s so massive that it, too, will live only a short while. Then, like its neighbor, it’ll expand and shine brilliantly — making the teapot much more prominent.
 

Script by Damond Benningfield

Support McDonald Observatory