March 28, 2010

Sky Chart: What's Up in April

Yes, it's a month with plenty to watch in the heavens


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click image to enlarge

This chart represents the sky as it appears over Maine during April. The stars are shown as they appear at 10:30 p.m. early in the month, at 9:30 p.m. at midmonth and at 8:30 p.m. at month’s end. Mars and Saturn are shown in their midmonth positions. To use the map, hold it vertically and turn it so that the direction you are facing is at the bottom.

Sky chart prepared by George Ayers

The last subtle event will be the Lyrid Meteor shower. They will peak on Thursday morning the 22nd, which also happens to be the 40th anniversary of Earth Day. The Lyrids usually only produce about 15 to 20 meteors per hour, emanating from the constellation of Lyra, but this time the numbers will be fewer due to the moon being just six days before a full moon that night.

Saturn is just past opposition now, so it is rising in our eastern sky before sunset. It is located near the head of Virgo, close to the richest region of the Virgo Galaxy Cluster. This is an amazing cluster containing around 2,000 galaxies located 50 million light years away and stretching across 10 million light years of space. This cluster is much richer than our own little cluster, called the Local Group, which consists of 30 galaxies, including the Andromeda and our home galaxy, the Milky Way. Expanding even farther out to a diameter of 100 million light years, both of these clusters are part of the much vaster Virgo Super cluster of galaxies, which consists of 100 individual galaxy clusters, including our own.


April 1. On this day in 1997, Comet Hale-Bopp made its closest approach to the sun.

April 3. Orange Antares, which means "rival of Mars," will be just one degree below the waning gibbous moon this morning one hour before sunrise.

April 6. The last-quarter moon is at 5:37 a.m.

April 7. On this day in 1991 the Compton Gamma Ray Observatory was deployed into low earth orbit of only 280 miles up to avoid the Van Allen radiation belts. It discovered nearly one extremely energetic and powerful gamma ray burst per day during its nineyears in orbit. It was brought back down on June 4, 2000.

April 11. The waning crescent moon will be 5 degrees above Jupiter this morning before dawn.

April 12. On this day in 1961, Yuri Gagarin became the first human in space.

April 15-16. The slender waxing crescent moon will be near Mercury and Venus this evening, and near the Pleiades the next evening one hour after sunset.

April 16-18. Mars will drift directly above the Beehive star cluster in Cancer these evenings.

April 21. The first-quarter moon is at 2:20 p.m.

April 23. Max Planck, a German physicist, was born on this day in 1858. He developed quantum mechanics that showed the dual wave-particle nature of photons and electrons.

April 23-25. Venus and the Pleiades fit into a 5-degree field of view these three evenings.

April 25. The Hubble Space Telescope was deployed on this day in 1990. It's still taking great pictures 20 years later.

April 28. The full moon is at 8:18 a.m. This is also known as the Grass, Egg, Pink or Fish Moon.


Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.


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