Dancing Planets

I know that it has been cloudy and rainy, but if we get a clear morning and/or evening it will be well worth your time to take the kids and spend some time under the early morning and evening skies. If you have been to the Planetarium you have heard me talk about our five naked-eye planets, Mercury, Venus, Mars, Jupiter, and Saturn. These were the planets that the ancient peoples knew as the wanderers.  Naked eye means that you don’t need binoculars or a telescope to view these planets. All you have to do is use your eyes and look up. Four of these planets are putting on a show for us right now.

Let’s start in the morning sky. You’ll need to go outside about an hour before sunrise and look low to the southeast. There you will see the constellation of Sagittarius, the Centaur with his bow. The most recognizable part of this constellation is the teapot shape. Look to the east of the teapot and you will find Jupiter, Mars and Saturn. Jupiter will be the brightest object in this part of the sky. To its left will be red Mars and to the left of Mars will be Saturn, bright but not as bright as Jupiter. Because Mars is closer to Earth than Jupiter and Saturn it moves eastward

more quickly.  A conjunction happens when two objects appear to be close together from our perspective on Earth. As Mars has moved through the sky it passed close to Jupiter on March 20, the first full day of spring, and will pass close to Saturn on March 31. Now each of these conjunctions on their own would draw world-wide attention among amateur astronomers and enthusiasts, so to have these two conjunctions in the same month is an incredible treat. And indeed, it is a very rare treat. Jupiter and Saturn appear near each other approximately every 20 years. The last time all three of these planets came this close was April 2000.

Now let’s go outside about an hour after sunset and look to the west. There you will see Venus. Venus is the brightest object here dominating the western evening sky. I promise you can’t miss it. Venus reaches greatest elongation east on March 24. What is the greatest elongation?  Elongation is the angular separation between the Sun and a planet, with Earth as the reference point. The greatest elongation of an inferior planet occurs when the planet’s position, in its orbital path around the Sun, is at a tangent to the observer on Earth. The inferior planets are Venus and Mercury because they are inside the orbit of Earth. To the Earth observer, Venus and Mercury appear to be at their farthest point from the Sun. When Venus or Mercury reach their greatest eastern elongation, they are visible in the evening sky after sunset. When they are at greatest western elongation they are visible in the morning sky before sunrise. After the greatest elongation east or west they appear to move closer to the Sun until they pass in front of or behind the Sun.