Three planets line up for rare show
Posted May 23, 2013
Jupiter, Venus and Mercury will be perform a shell game of sorts in the evening sky.
Each night this week, Mercury will slide above and Jupiter will move down to join Venus. By Sunday, this will form the closest grouping of planets we will see for more than 10 years, and you wont need a telescope to enjoy it. Your best opportunity to view this collection of planets is about 45 minutes after sunset.
Wednesday night, Jupiter appeared above and to the right of very bright Venus. Dimmer and smaller Mercury appeared nearly along side Venus. As the week continues, Mercury will move higher passing Venus and Jupiter lower drawing closer to Venus. By Sunday the three planets will form a nearly perfect triangle, something we wont see again for more than 10 years.
These planets will be so close you should be able to cover them all with your thumb held at arms length (a little more than 2 degrees, your pinky is about 1 degree or 2 widths of the moon). They may appear to be close but Venus is 46 million miles from Mercury, and 411 million miles from Jupiter.
Next week, these three planets will form a line pointing up to the constellation Gemini. If you continue to look to the northwest over the next couple week's you'll see tiny Mercury grow brighter as it reaches it's highest point in the sky the first week of June.
The other astronomical event on astronomers calendars wont be nearly as spectacular. The second lunar eclipse of the year occurs Saturday night but is of more interest to academics than skywatchers. During this penumbral eclipse, the moon just grazes the Earth's outer shadow.
The dimming will be so slight, it will be imperceptible.
Tony Rice is a volunteer in the NASA/JPL Solar System Ambassador program and software engineer at Cisco Systems. You can follow him on twitter @rtphokie.