STAR TRAK for May 2011

May 06, 2011
Venus. Photo courtesy of NASA

The closest gathering of four bright planets in decades will be on display low in the eastern sky before dawn during May.

Unfortunately, at mid-northern latitudes these planets will be only a few degrees above the horizon a half hour before sunrise for most of the month. In the the gathering will be considerably higher in the sky.

Venus, Jupiter, Mercury and Mars will fit within the field of view of binoculars on May 12, and within a circle of 10 degrees from May 2 to May 19. Jupiter will leave the group after that, but the other three planets will remain tightly clustered until almost the end of the month.

Brilliant Venus will be easy to spot with the unaided eye all month. Mercury and Mars will be so low in bright twilight that they will be difficult to find without optical aid.

From May 7 to May 15, Venus, Jupiter and Mercury will form a "trio" -- three planets within 5 degrees of one another.

The highlight of the month will be on May 11, when Jupiter will be less than 1 degree to the upper left (north) of Venus. On both May 11 and 12, the Venus-Jupiter-Mercury trio will be near its tightest.

From May 15 to May 25, Venus, Mercury and Mars will form a second tight trio. They will be closest on May 21.

After May 25, these will quickly move apart.

As evening twilight fades during May, bright yellow Saturn will come into view in the southeastern sky. It will be highest in the south around 11 p.m. EDT at the beginning of the month and two hours earlier by month's end. The white star Spica will be about 15 degrees to Saturn's lower left (east) and about the same brightness.

Saturn's rings will be tilted 8 degrees to our line of sight. Its largest moon, Titan, will be due south of the planet on May 3 and 19 and due north on May 11 and 27.

Meteor shower

This month, Earth will encounter a stream of dust left behind in space by Comet Halley, causing the Eta Aquarid meteor shower that will peak before dawn on May 6. The shower will be active for a few days before and after the peak as well.

The meteors will appear to come from a point called the radiant in the constellation Aquarius, which will rise in the east about two hours before the start of morning twilight. The higher this point is above the horizon, the more meteors will be visible. The crescent moon will set before midnight, so a clear, dark sky will offer ideal conditions for meteor-watching.

Observers in the Northern Hemisphere may see around 25 meteors per hour, because Aquarius will be close to the eastern horizon. Those watching in the Southern Hemisphere will see Aquarius much higher in the sky, and there may be as many as 70 meteors per hour at the peak.

Moon phases

The moon will be new on May 3, at first quarter on May 10, full on May 17 and at third quarter on May 24.

Explore further: After early troubles, all go for Milky Way telescope

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