Monday, April 21, 2014
By BERNIE REIM
(Continued from page 1)
This chart represents the sky as it appears over Maine during August. 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. Saturn is shown in its midmonth position.
Sky chart prepared by George Ayers
It is fitting that Saturn is now the only bright evening planet after Venus sets in the west just one and a half hours after sunset. Notice that Venus will appear to be rapidly catching up with Saturn in our evening sky this month. They will start 53 degrees apart and end up just 18 degrees apart, or less than two fists at arm's length, by the end of this month.
To add to the drama, a slender waxing crescent moon will show up just below Venus on Aug. 9 about half an hour after sunset, low in the west-southwestern sky. Then keep watching as the moon drifts close to Spica by the 11th and near Saturn on the 12th, when the Perseid meteor shower will peak.
This will be a good year for this famous meteor shower caused by the earth passing through debris from Comet Swift-Tuttle, zipping into our upper atmosphere at nearly 40 miles per second. This is basically comet dust, about the size of a grain of sand. The moon will have set a few hours before midnight, so it will not interfere with the best part of the shower, which is usually between midnight and dawn. You could see up to 100 meteors per hour this year from a dark sky site. Look northeast towards Perseus to see where these meteors will come from, but you could see them anywhere in the sky, although you will always be able to trace them back to their radiant in Perseus. Be aware that you may also see some late Delta Aquarids and Kappa Cygnids, along with some stray meteors that are not part of any of these showers. The best mornings this year will be Monday the 12th and Tuesday the 13th.
Look for Mercury, Mars and Jupiter in the eastern morning sky 45 minutes before sunrise for the first half of this month. Then keep watching as Mercury drops out of the picture, and Mars and Jupiter get a little higher and brighter in our sky.
• Aug. 3. A waning crescent moon will be near Jupiter this morning. The Messenger spacecraft was launched to Mercury on this day in 2004.
• Aug. 4. The moon will be near Mars this morning.
• Aug. 5. The moon will be below Mercury in Gemini this morning, 45 minutes before sunrise.
• Aug. 6. New moon at 5:51 p.m.
• Aug, 9. The waxing crescent moon will be near Venus this evening half an hour after sunset low in the west-southwestern sky.
• Aug. 10. On this day in 1990, the Magellan spacecraft entered orbit around Venus.
• Aug. 11. On this day in 1877, Asaph Hall discovered Deimos, the smaller of the two moons of Mars at about eight miles in diameter. He would discover Phobos, at about 14 miles in diameter, just 6 days later. They are thought to be captured asteroids and they are just temporary moons since they will crash into the red planet in a few million years.
• Aug. 12. The Perseid meteor shower peaks this morning and the next.
• Aug. 14. First quarter moon is at 6:56 a.m.
• Aug. 20. Full moon is at 9:45 p.m. This is also known as the Sturgeon, Green Corn or Grain Moon.
• Aug. 22. On this day in 1963, the X-15 set a world altitude record of 354,000 feet, or 67 miles high. That is about the altitude where the northern lights take place and most of the meteors burn up as our upper atmosphere starts to get a little denser at that height.
• Aug. 24. On this day in 1989, Voyager 2 flew past Neptune. I remember that they had live commentary from scientists at JPL during a program called "Neptune All Night."
• Aug. 28. On this day in 1789, William Herschel discovered Enceladus, which is the sixth-largest of Saturn's 62 moons. Since then it was discovered that this moon has cryovolcanoes that shoot large jets of water ice into space, some of which falls back as snow and some of which adds to and interacts with the rings of Saturn. Last-quarter moon is at 5:35 a.m.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.