Sky Lights

Check out dusk's dazzling display of the evening star

By Bob Berman|Tuesday, June 01, 1999

Only spacecraft like Russia's Venera
probes could spot detail like this on Venus.
But in June you"ll do almost as well with
just your eyes, as the planet should put on
the show of the decade.

Courtesy NASA

If you think good sky watching only comes withdeep, dark nights, look up this month. June's long hours of duskfeature magnificent sights, including an extraordinary presentation ofVenus. In terms of brilliance for size, Venus is by far the mostluminous object in the night sky, so bright it will no doubt inspire aflood of UFO sightings.

Because Venus circles the sun exactly 13times for every 8 orbits Earth completes, it faithfully repeats itsposition and characteristics in our sky on an eight-year cycle. Forexample, the planet was last this brilliant in 1991, assuring us of adazzling return this year.

Venus makes an outstanding eveningstar just three or four years out of every ten. And even in the goodyears, it's high and bright only from midwinter to late spring. Duringthat time the planet's orbital path stretches upward, placing it farabove the horizon. At other times it travels leftward from the settingsun, putting it low in the sky and forcing us to view it through theobscuring atmosphere. So next year Venus will be a bit of a dud, as ithas been in the past couple of years.Sometimes finding the perfect timeto view Venus demands a compromise. The planet won't shimmer itsbrightest until next month. But last month Venus occupied its highestperch of the year. This month the planet will be nearly at its highestand nearly at its brightest. The view will be even better because inJune, Venus swings out to the edge of its orbit, far from the glare ofthe sun. Venus and the sun will be maximally separated, by a full 45degrees, on June 10.

From June 12 until month's end, zippyMercury will also climb to the edge of its orbit and stand at its best.To find it, just look for the bright light nestled between Venus andthe point on the horizon where the sun sets. Mercury is not as brightas Venus, but it's worth finding because it puts in its last decentevening-sky appearance of the year.

The best way to get a facefull of Venus and Mercury is to look west about 40 minutes aftersunset, around 9 P.M. You'll have no trouble spotting Venus. Itscreamy, steady radiance will be 60 times brighter than the brightestsummer star. To the naked eye the planet is a dazzling point, and withany low-power telescope you can see a lovely half-moon shape. Butremember, as you admire its beauty, that Venus's clouds of sulfuricacid, its ultrahigh air pressure, and its blistering 900-degreetemperatures make it a hellhole in a rogues' gallery of unpleasantplanets. (The first spacecraft to land there, Russia's Venera in 1970,was pressure-cooked into oblivion 23 minutes after touchdown.)In thecoming weeks Venus will sink lower in the sky, even as it grows morebrilliant. On July 15 it will form a tight triple conjunction with thecrescent moon and Leo's blue star Regulus. By the end of July, Venuswill vanish, not to appear again until January 2001. For the rest ofthe year, twilight will be starkly void of any bright stars or planets.So before the emptiness arrives, peek out the window to see Venus'slast showstopping act.

The Venus Hypermap
Venus Photo Gallery
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