A Triangle of Planets!

A trio of bright planets will gather together in the Name A Star Live constellation “Virgo” in early August, putting on quite a show for stargazers around the world!

To enjoy this heavenly treat, go outside about 45 minutes after sunset each night during the first week of August and face west.  (See diagram below.)  The red planet Mars, the beautiful ringed planet Saturn, and the hot and cloudy planet Venus will fly in a triangular formation that will change from night-to-night.

Triangle of Planets
Mars, Saturn, Venus and Mercury -- toward the western horizon -- about 45 minutes after sunset on August 28

Moreover, if you have a good, clear view of the western horizon you might also see the elusive planet Mercury.  If trees, buildings, hills or other structures are in your way, try to observe Mercury from an elevated location, like a hilltop or an upper-level office in a skyscraper or other building.

Back to the planetary triangle:  On August 1, Mars and Saturn will be quite close to one another, while Venus will stand aloofly apart.  But over the course of the next week, Venus will lose its shyness and gradually move closer and closer to Mars and Saturn.  By August 8, the three planets will form a compact triangle.

But don’t let appearances fool you!  While these three planets may appear to be close to one another, in reality they are quite far apart: On August 8, Saturn will be about 951 million miles (1.5 trillion kilometers) from Earth; Mars will be about 190 million miles (305 million km) from Earth; and Venus will be a paltry 72 million miles (115 million km) from Earth.  To put all that in perspective … If you could drive your car to nearby Venus at the leisurely rate of 55 miles per hour (about 89 km/hour), it would take you 149 years to get there!

Get a rare look at Mercury — Venus too!

April 2010 is a particularly good time to see the planet Mercury.  Mercury is the innermost planet to the sun, and is thus difficult to observe.  But you can get a good look at Mercury in early April this year, especially if you live in the northern hemisphere of Earth.

Look toward the west at sunset (being careful not to look at the sun!).  You should see two bright points of light above the western horizon.  The object on top is the planet Venus, and the object beneath that is the planet Mercury.   Both planets are in the constellation Aries, which is a Name A Star Live constellation.  So if you have a star in Aries, then if you find Venus and Mercury, you know your star is nearby!

Venus and Jupiter at Sunset
Venus and Jupiter shortly after sunset, June 2002. Credit: NASA

Mercury and Venus will appear closest together on the evenings of April 3 and 4.  Again, the best views will be from the northern hemisphere of Earth.  If you live in the southern hemisphere, then the two planets will appear so close to the western horizon at sunset that you may not get a good view.  (Again, don’t look at the sun!)

If you observe the two planets through a telescope. you’ll notice that Venus looks like a bright, almost-full circle, while Mercury looks like a semi-circle — or even a crescent shape.  This is because Mercury is so very close to the sun that we never really see the full face of the planet.

Don’t wait!  Your best views of Venus and Mercury will be in the first week to 10 days of April.