Saturday, December 7, 2013
By BERNIE REIM
Summer started in late June, so this will be the first full month in the northern hemisphere. Even though the days will be long and the nights will be short, this will be a great month to get out under the warm skies and continue to learn more about where we really are and to better appreciate the great celestial motions always going on all around us.
SKY GUIDE: This chart represents the sky as it appears over Maine during July. The stars are shown as they look 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 and Venus 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
Hopefully some of you had a chance to discover the meaning of the summer solstice by keeping close track of exactly where the sun sets each evening for a period of time before and after the solstice. If not, you will have another chance in six months.
It's important to spend some more time outside around the seasonal changes to become more aware of what the sun is doing in relation to the earth. I encourage you to do this during any time of the year and you will discover many interesting new things about natural cycles and the relationship of the sun to the earth.
You will find that on one hand we do live in a perfect Newtonian mathematical, clockwork solar system, but on the other hand we also live in a much more open, dynamic and rapidly changing universe.
I experienced the dark skies of northern Maine for one night last month while at Roaring Brook campground at Mount Katahdin. I watched spellbound for hours as several moose, a deer and some mergansers worked their way across Sand Stream Pond toward sunset. With a great view and reflections of Mt. Katahdin and several other mountains around that pond, these creatures exemplified the essence of wilderness in that wonderful natural setting. Everything they could ever need was provided.
The night was crystal clear and the brook really was roaring. The next morning I watched the sun's rays cast across the top of the mountains, as they had for thousands of years since the glaciers retreated and carved out this dramatic landscape at the end or beginning of the Appalachian Trail. When you look for astronomical events, it is important to also tune in to many other things going on all around you in the natural world to greatly enrich your experience and make it more meaningful for you.
This month offers its usual share of nice planetary conjunctions and even a meteor shower. We don't have a super moon this month, but we do have a full moon that will rise far south of east and set far south of west and never get very high in the sky, essentially creating the opposite path the sun creates near its peak high in the sky near the summer solstice. It is also very interesting to watch how high in the sky the full moon gets near the winter solstice as the sun traces a very low arc through our sky at that time.
Saturn now rules the evening sky as Jupiter dropped below the horizon last month. The ringed planet will end its retrograde or westward motion against the fixed background of stars on July 9, so it will appear stationary near the boundary of Libra and Virgo all month. It is easy to recognize Saturn in our sky about 15 degrees to the left of Spica, the brightest star in the constellation of Virgo.
Look for the beautiful golden hue of Saturn and compare it to the bluish white color of Spica, the 15th-brightest star in our sky along with Antares in Scorpius. Spica is Latin for ear of wheat, and is named after the Greek goddess of the harvest, which is Ceres, also the name of the first and largest of all of our asteroids.
This is a good time to look at Saturn through a telescope because it will be at eastern quadrature on the 24th, which means it will be exactly 90 degrees east of the sun. That means that Saturn's black shadow is now especially wide on its magnificent and extremely thin ring system.
Located 260 light years away from Earth, Spica is a very interesting double star. Both stars are larger and hotter than our sun, and they whirl around each other every 4 days at a distance of just 11 million miles, which is about 10 times closer than the distance to our sun. Even with a large telescope you would only see one star where Spica is. But based on lunar occultations, there could be as many as three more stars in this system, making this a star system where only Spica appears. All the stars are truly much more dynamic than they appear to be and they all hold a myriad of unsolved mysteries, since we still know so little about their true nature and their enormous power and how we could harness it.
Spica's distance places it where the light of the turbulent events leading to our Revolutionary War would now be located. In other words, if someone on a planet around Spica would have a powerful enough telescope to see details on Earth, they would see exactly what was happening in the 1750s, and not just in this country. They would be seeing that right now, this second, but they would be unable to change anything or get a message back to us about exactly what happened.
You can extrapolate that whole scenario to any distance in space and to any other galaxy you would want to choose. If you went to the Andromeda Galaxy, our sister galaxy located about 2.5 million light years away between the constellations of Cassiopeia and Pegasus, you would see exactly what happened on Earth 2.5 million years ago, and you would be seeing that right now, this very second. That illustrates an important principle and starts to give you a better sense of the fourth dimensional space-time continuum that we really live in instead of the very limited three-dimensional world that we appear to live in.
Venus will stay low in our western evening sky, setting just 1.5 hours after sunset for most of the summer. It is only 10 degrees high, or one fist held at arm's length, by the time it is easily visible half an hour after sunset. Watch for a very close conjunction of just over one degree apart of Venus and Regulus in Leo 45 minutes after sunset on the evening of July 22. Watch a slender waxing crescent moon drift past Venus and then Regulus during the evenings of July 10th through the 12th.
The Delta Aquarid meteor shower will peak during the morning hours of July 29. You could only expect about 20 meteors per hour, and some of those will be washed out by the moon, which will be last quarter, meaning that it will rise around midnight. This shower is better in the southern hemisphere, just like the May 4 Eta Aquarid shower, caused by Halley's Comet. The Delta Aquarids are probably caused by Comet 96 p/Machholz, which was just discovered in 1986. Last year at this time, both the comet and the meteor shower it created were visible in the sky at the same time.
• July 4. On this day in 1054, Chinese astronomers along with native Americans at Chaco Canyon observed the supernova in Taurus that is now M1, or the Crab Nebula.
• July 5. Earth is at aphelion, or farthest from the sun today at 94,509,959 miles, or 1.7 percent more than its average distance and 3.3 percent farther than its perihelion distance in January. Look for a waning crescent moon near Aldebaran in Taurus a half-hour before sunrise.
• July 6. On this day in 1687, Isaac Newton published his Principia book.
• July 8. New moon at 3:14 a.m.
• July 15. First-quarter moon at 11:18 p.m.
• July 16. On this day in 1994, the first of 21 fragments of Comet Shoemaker-Levy 9 impacted Jupiter. I was lucky enough to witness five impacts first hand over the next six days.
• July 22. Mars and Jupiter will be less than one degree apart 45 minutes before sunrise low in the east-northeastern sky in Gemini. Mercury will be visible below this pair. Bring binoculars. At dusk on that day, Venus and Regulus will be just over one degree apart. Full moon is at 2:16 p.m., also called the Hay or Thunder Moon.
• July 29. Last-quarter moon is at 1:43 p.m. The Delta Aquarid meteor shower peaks this morning.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.