Just Passing By Venus
Last Friday, June 11, Venus reached its greatest apparent distance from the sun in 1999 (45o). For the rest of June and most of July the second planet from the sun lies 30 to 40 degrees above the western horizon as the sun sets. Blazing at magnitude -4.3, it's nearly impossible to miss. Venus is so bright that it is frequently mistaken for an airplane or a UFO.
Right: Artist Duane Hilton created this image showing the June 16th close encounter between Venus and the Moon as they would appear over the horizon of Utah's Bryce Canyon after sunset. As viewed through a telescope Venus will look like a tiny quarter Moon approximately 25 arcseconds across. The planet Mercury also makes an appearance this week, shining low on the western horizon at magnitude -0.2.
On Wednesday, June 16, sparkling Venus will gain a companion. The slender crescent moon will skim by Venus, passing just 3 degrees below the bright planet. It's a lovely sight that stargazers won't want to miss. Because Venus and the Moon are so bright they should be visible even through the glare of urban lights.
There will be another close encounter with Venus in June, but this one won't be visible to the naked eye. On June 24, NASA's Cassini spacecraft -- bound for Saturn -- will fly by Venus on its way to the outer solar system.
Above: This diagram from JPL shows Cassini's circuitous path to Saturn, featuring gravity assist flybys of Earth, Venus and Jupiter. Click for a larger image.
Venus is a popular place for such maneuvers. The image below shows Venus as it was seen by the Galileo spacecraft when it flew by the planet on its way to Jupiter in 1990.
Moonlight & EarthshineWednesday's close encounter between Venus and the Moon should be an enjoyable sight, but there's more: Cradled in the arms of the slim crescent Moon will appear the ghostly outline of the full Moon, a dim glow that astronomers call "Earthshine."
Sign up for our EXPRESS SCIENCE NEWS delivery
For those readers with a telescope, a look at Venus on Wednesday will be a rewarding sight. Because Venus is closer to the sun than Earth, it appears from our vantage point to have phases like the Moon. As viewed through a telescope on June 16th Venus will look like a tiny quarter Moon approximately 25 arcseconds across. Forty-six percent of the visible disk will be illuminated.
If you do look at Venus through a telescope don't expect to see any surface features. The planet is completely veiled by clouds. In fact, that's why Venus is so bright. Its dense cloud layer reflects most of the sunlight shining down on the planet.
December 3: Mars Polar Lander nears touchdown
December 2: What next, Leonids?
November 30: Polar Lander Mission Overview
November 30: Learning how to make a clean sweep in space
Mercury RisingThe planet Mercury also makes an appearance this week, shining low on the western horizon at magnitude -0.2. Mercury is rarely easy to see because it is always near the Sun, and picking it out of the Sun's glare can be difficult. Mercury will be making one of its best appearances of the year during the last week of June when its elongation, or apparent distance from the Sun, reaches 25.5 degrees. Perhaps the best day to view Mercury this week will be Tuesday, June 15, when Mercury lies 22 degrees from the Sun and the delicate crescent moon will be about midway between Mercury and Venus. An unobstructed view of the horizon is absolutely required for a clear view of the nearest planet to the Sun.
For more information about Mercury, Venus and the Moon, visit The Nine Planets by Bill Arnett and SEDS.
Cassini: Voyage to Saturn -- Cassini Mission home page
Venus: Just Passing By -- Astronomy Picture of the Day, May 1, 1998
A rare double-conjunction eclipse -- Astronomy Picture of the Day, Apr. 28, 1998
A Venus Landing -- Astronomy Picture of the Day, Jan. 24, 1999
Venus's Once Molten Surface -- Astronomy Picture of the Day, Jan. 10, 1999
Why is Venus so bright? -- from EarthSky.com
NASA's Magellan Mission to Venus -- from JPL
The Nine Planets: the Moon -- from SEDS
The Nine Planets: Venus -- from SEDS
The Solar System Photo Gallery -- from the National Space Science Data Center
More NASA Science News
return to Space Science News Home
|For more information, please contact:
Dr. John M. Horack , Director of Science Communications
|Author: Dr. Tony Phillips
Curator: Bryan Walls
NASA Official: John M. Horack