22 May 2013

The Dance of the Planets - a spectacular celestial alignment

This week is the culmination of a spectacular celestial alignment, creating a rare and beautiful triangle of three planets on Sunday 26th. The planets will be low in the west after sunset, and as the glare of the sunset fades, the three bright dots of light will emerge from that glare, and if you have a good western view, you'll see them for a short window of time before they set.

The Triangle of Planets
Jupiter has been dominating the night sky for months, but each successive night has brought it closer to the time when it slips 'behind' the Sun, from our vantage point, and is shielded from our view. This happens to all of the outer planets throughout the course of a year or two. But by cosmic coincidence, Mercury and Venus are rapidly rising into the sunset sky, as their orbits bring them out of the glare from being 'behind' the Sun, and they quickly pop up into the evening sky. This week, they appear to move higher and higher in the sky just as Jupiter is 'falling' and they cross over in a lovely pattern.

To see this spectacle, head out any evening and look west. The configuration will be changing noticeably each night, and for me, that is the real fun here -- to not only see a rare and unusual alignment on Sunday, but to watch the set up in the days before and after. Here are a number of good links with additional information:

Sky & Telescope Magazine
The Always-Engaging Tony Flanders on SkyWeek
NASA Science Cast

Enjoy the show, and may you have clear skies!

Image courtesy of Sky & Telescope

10 May 2013

Planetary Trio 'Warm Up Act'

During the month of May, three planets are going to move into a very close alignment, and the set up begins this week with the Moon adding some color to the scene for a few days. The two fast-moving inner planets, Mercury and Venus, are going to be coming into view in the west shortly after sunset, joining the massive Jupiter as it slowly fades out of view into the twilight. The dynamics of these changes is not easy to explain in a short blog post, but because of the fact that inner and outer planets appear to move differently from our Earth-bound perspective, the planets will all appear to 'cross over' in the west over the next few weeks, and the view should be dramatic.

The Moon adds color to the view.
This weekend, the show starts with Venus emerging from the glare of sunset into the western sky. You'll need a low western horizon to see this, in particular with the young Moon on the 10th. The alignment of Jupiter, the Moon and Venus on the 11th should be nice, and then as the Moon rapidly moves out of the scene, look for Venus (and shortly thereafter Mercury) to move up higher and higher in the twilight sky, leading to a much more spectacular lineup. More on that in my next blog post.

Image courtesy of Sky & Telescope.