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Hal Kibbey

Last modified: Wednesday, April 1, 2009


Mercury meets the Pleiades in April

April 1, 2009

BLOOMINGTON, Ind. -- For observers at mid-northern latitudes, Mercury will make its best evening showing of the year during the second half of April, when it will appear near the Pleiades star cluster low in the west-northwest after sunset. Binoculars will provide a fine view of the spectacle. On April 9, Mercury will be as bright as the sky's brightest star, Sirius.

The Pleiades (pronounced PLEE-ah-deez) are lovely by themselves, and on a clear night they can be seen with the unaided eye low in the west in the constellation Taurus the Bull. Known prehistorically, the cluster is identified as a group of women in many cultures around the world, from Australian Aborigine to Native American. A photograph of the Pleiades can be seen at and other Web sites as well.

Saturn will be high in the southeast as darkness falls on April evenings, one of the first "stars" to appear. It will be visible much of the night in the constellation Leo the Lion, to the lower left (east) of Leo's brightest star, Regulus. Saturn's rings will be tilted only a few degrees from edgewise during April, but the planet will still outshine both Regulus and Spica, the brightest star in the constellation Virgo the Virgin much farther to the lower left.

Venus will gleam dazzlingly bright even in morning twilight during April. Rising less than an hour before the sun at the beginning of the month, by month's end it will appear almost two hours before sunrise in a darker sky. At mid-northern latitudes Venus will remain low in the east all month, but observers in the Southern Hemisphere will see this beautiful "morning star" climb much higher and brighten even more as the month progresses.

Jupiter will rise more than three hours before the sun by the end of April, but in spite of that it will still be rather low in the southeast at dawn. Not until later in the year when Jupiter is clear of the murk near the horizon will we have good views of its four largest moons, which Galileo discovered with one of the first telescopes.

Mars will be faint and hard to find during April, hovering above the southeastern horizon.

Light pollution

A great deal of energy and money is wasted on inefficient, improperly directed outdoor lighting. To help call attention to this problem of light pollution, the International Dark-Sky Association encourages people in the United States to turn off unnecessary outside lighting during National Dark-Sky Week. This year NDSW will be from April 20 to April 26. More information is available at

Meteor shower

The Lyrid meteor shower will peak during the hours before dawn on April 22. The moon will be just two days from new, so viewing conditions should be favorable. About 20 Lyrids per hour are normally visible. The meteors can appear anywhere in the sky, but they will seem to come from a point called the radiant in the constellation Lyra the Harp, which gives the shower its name. Lyra's bright white star Vega will be almost at the radiant, and the meteor count should be highest when Vega is well above the eastern horizon, beginning around midnight local time in the Northern Hemisphere and lasting the rest of the night. The later the hour, the more meteors there will be.

Summer Triangle

If you're wary of the weather these days, a reliable sign that the seasons really are changing is the appearance of a trio of bright white stars called the Summer Triangle. Vega will be the first to rise each night in the east, leading the way high across the sky. The other stars are Altair in the constellation Aquila the Eagle to the south and Deneb in the constellation Cygnus the Swan to the north. When you are looking from Deneb to Altair, you are also looking at the Milky Way, though it's usually obscured by city lights. If you find a place dark enough for you to see the Milky Way, keep the location in mind -- you'll also see a lot more meteors and other celestial objects from there. A photograph of the Summer Triangle is at Click on the photo to enlarge it. If you have trouble picking out the three brightest stars, click on "labels on/off" to identify them.

Moon phases

The moon will be at first quarter on April 2, full on April 9, at third quarter on April 17 and new on April 24.