for National Geographic News
This evening at twilight, two universal symbols of beauty will shine together in the western sky, creating a stunning sight for North and South Americans.
The planet Venus, the mythological representation of the goddess of love and beauty, will be seen very near the crescent moon, a night object with its own claims to beauty.
"This will be a real head turner," said Alan MacRobert, a senior editor at Sky and Telescope magazine. "You will not have to be some kind of expert astronomer for this. People are going to see this out of their front windshields driving home from work and say, What's that?!"
The pairing of these two bright celestial objects will be plainly visible to the naked eye, MacRobert said, although binoculars could help enhance the experience. "Any old pair of binoculars that you have knocking about the back of a closet some place is a perfectly good astronomical instrument, and you ought to bring it out for this."
Venus is considered to be Earth's "sister" planet because of its relatively similar size. However, with a surface temperature of approximately 700 degrees Celsius (1,300 degrees Fahrenheit) and an atmospheric pressure equivalent to that at an oceanic depth of 2,000 feet (610 meters), Venus is "not nice real estate," MacRobert noted.
Venus, though a planet, is often called the morning star or the evening star. Located second from the sun, Venus is always close to the sun's location in the Earth's sky, MacRobert said, and so is visible only as a very bright spot in the east before sunrise or the west after sunset.
Apparent sky pairings such as the one between Venus and the moon tonight are known in astronomical terms as conjunctions, explained Walter Nissen. Nissen is a career mathematician and a former president of the National Capital Astronomers organization located in Washington, D.C.
Conjunctions occur only because the planets in this solar system (with the exception of Pluto) and Earth's moon lie within the same plane, Nissen said. These objects share the same plane because they all formed from the same thin disc of dust that orbited the sun at the time the solar system developed.
Venus itself goes through five apparitions, or phases of visibility, over an approximate eight-year time span, Nissen said. Currently, Venus is going through a highly visible phase and will be at its greatest brilliancy on May 1.
A unique conjunction between Venus and the sun will occur on June 8 of this year. Known as the transit of Venus, this event involves the apparent passage of Venus in front of the sun. This event, which last occurred in 1882, can be witnessed only with the use of special protective filters, Nissen cautioned.
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