Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.
Find more columns by Westlake here.
Ancient Greek skywatchers recognized five star-like objects that slowly moved through the stationary constellations. They called them planets, meaning "wandering stars," and four of these five planets are visible now in our evening sky.
The brightest and most striking is Venus, the so-called "evening star" lighting up the western sky at dusk. Venus will be at its greatest elongation from the sun June 8. What that means for us is Venus will appear as far from the sun as it can in our evening sky, so it stays up for several hours after the sun goes down. It also means Venus shines at its brightest. Some folks claim to have seen their shadow cast by the light from Venus.
If you have a clear view of the western horizon, now is an excellent chance to spot the only planet closer to the sun than Venus: Mercury. Try looking for a bright "star" about one hand-span held at arm's length from Venus in the 4 o'clock position. While not as bright as Venus, Mercury stands out in the deepening twilight. Mercury reaches its greatest elongation from the sun June 1 and will pass out of view by mid-month, so catch it early.
At the 10 o'clock position from Venus, you can spot another planet: Saturn. Keep an eye on this pair of planets during June as the distance between them shrinks to only two-thirds of a degree by June 30. On that night, the two will form a striking duo high in the western sky after sundown and will both fit into the field of view of a small telescope at the same time. That's a "Wow" moment you won't want to miss.
To find the fourth June planet, you'll need to turn your back on Venus and Saturn and face the southeastern sky. There, you'll have no trouble spotting the giant planet Jupiter, rising above the mountains near the red star Antares. Jupiter reaches opposition - its closest point to the Earth for the year - June 5.
Only Mars is missing from this parade of planets. By the time Mars rises at about 2:30 in the morning, Mercury, Venus and Saturn have left the scene.
There is one other planetary object that you can glimpse this month, not far from the planet Jupiter. Heralded as a new planet when it was discovered 200 years ago, this object was subsequently demoted to the status of an asteroid. We know it as Vesta. When closest to Earth, as it is now, Vesta can become bright enough to glimpse with the unaided eye in a dark clear sky. Try looking about one fist-width at arm's length at the 1 o'clock position from Jupiter.
Have fun watching the parade of planets this June!
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the Web sites of CNN.com, NASA's "Astronomy Picture of the Day," Spaceweather.com, Space.com, Discover.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His "Celestial News" article appears weekly in the Steamboat Pilot & Today.