Saturday, April 19, 2014
By BERNIE REIM
The month of April is named after aprilis, which means aperture, or opening. This is what is starting to happen now across the northern hemisphere, as spring will slowly transform our landscape this month.
A similar shift in the sky will be taking place as the familiar winter hexagon will slowly sink into the western horizon and the summer triangle will be rising over the eastern horizon.
The king of the planets, Jupiter, will relinquish its reign as the second-largest planet; Saturn will reach opposition by the end of the month. Other than this changing of the celestial guard, two other interesting events will happen this month. The annual Lyrid meteor shower will peak early Monday, April 22, which is also Earth Day. Then Comet PanSTARRS will get a little higher in our western evening sky even as it slowly gets fainter as it continues to recede from the earth and sun.
I finally saw the comet for the first time on the evening of St. Patrick's Day. I was out on a frozen lake with some friends and we started searching for it soon after sunset. It was a crystal clear, cold and calm evening as the afterglow from the receding sun slowly faded, allowing the gathering dusk of the twilight to reveal the brighter celestial objects one by one, as if they were materializing out of thin air.
Brilliant Jupiter was perched directly above a crescent moon, with the orange giant star named Aldebaran in Taurus the Bull just to the left of the moon. Just to the right, the Pleiades were also gaining in prominence as we plunged deeper into the shadow of our own earth. The subtle and mysterious earthshine reflecting off the unilluminated part of the moon added another element of beauty to a frigid, peaceful evening.
I suddenly spotted the comet low above the tree line across the lake. Its tail was about two degrees long and it had already taken on a subtle orange hue as it descended into the thicker part of our atmosphere. Once I found it in binoculars, we could see it easily for the next 10 minutes without optical aid before our western horizon would swallow it for the evening.
Its name is an acronym for the panoramic survey telescope and rapid response system located in Maui. This is a 1.8 meter $25 million telescope dedicated to searching for potentially hazardous asteroids that may hit the earth. They plan to build three more PanSTARRS telescopes in the near future.
Jupiter is still quite bright in our western evening sky, but it will get progressively lower toward the end of the month. Watch as a thin waxing crescent moon passes by the Pleiades, then the Hyades, and then Jupiter on the consecutive evenings of April 12-14.
Saturn will take over the role of ruling the night toward the end of the month. The ringed planet will reach opposition on April 28. Opposition is always the best time to view a superior planet since it will be closest to the earth and appear at its largest and brightest for the year. On that day Saturn will rise at sunset, reach its highest point at midnight and not set until sunrise. However, it will remain brighter than usual throughout the spring. Its rings will be tilted open about 19 degrees and you will be able to see several of its 62 moons through a telescope. Watch the nearly full moon pass just under the star Spica in Virgo one hour after sunset low in the southeastern sky on the 24th, then watch it pass just below Saturn, 12 degrees farther east, the next evening at the same time.
The other major highlight this month will be the Lyrid meteor shower. It will peak on Monday morning the 22nd. Since the moon will be just three days before full, you will only have a narrow window of time to watch the shower without moonlight. The waxing gibbous moon will not set until about a half-hour before dawn starts to brighten the sky and wash out the fainter meteors. You could see meteors anywhere in the sky, but they will all appear to originate from one point, called the radiant, close to the star Vega in the constellation of Lyra, which is part of the famous and easy-to-find summer triangle.
Try not to look right at the radiant; any of those meteors will leave shorter streaks because they will be traveling directly toward your line of sight. In 1983, a satellite discovered a disk of dust around Vega, which inspired Carl Sagan to write "Contact."About 10 years later we did discover two possible planets in this dust ring in infrared light. Now we know of nearly 1,000 exoplanets in other solar systems, with many more potential candidates being constantly discovered.
Caused by Comet Thatcher, which orbits the sun every 415 years, you can expect about 20 to 25 meteors per hour from a dark sky sight. Sometimes this shower surprises us and could produce up to 90 meteors per hour, as it did in 1982. The Lyrids will be smashing into our thin upper atmosphere at around 50 kilometers per second, which is 110,000 miles per house, which is about 40,000 mph faster than the earth continually orbits around the sun. Smaller than a grain of sand and even less dense, these tiny pieces of Comet Thatcher will create many short-lived streaks of light as they disintegrate about 70 miles high. You can expect several bolides, which will create shadows on Earth as they explode and cause a twisting debris trail that could last for several minutes.
• April 2. On this day in 1845, the first photograph of the sun was taken.
• April 3. Last quarter moon is at 12:37 a.m.
• April 7. On this day in 1991, the Compton Gamma Ray Observatory was deployed. It discovered many incredible high-energy events in the universe, including nearly one gamma ray burst per day over its nine-year life. It was taken out of orbit on June 4, 2000.
• April 10. The new moon is at 5:35 a.m.
• April 15. On this day in 1867, Wilbur Wright was born. On Dec., 17, 1903, the Wright Brothers made their first sustained powered flight 20 feet above the beach in Kitty Hawk, N.C. It only lasted for 12 seconds and traveled 120 feet. We then flew all the way to the moon and back just 651/2 years later.
• April 22. The Lyrid Meteor Shower peaks this morning about two hours before sunrise.
• April 24. On this day in 1970, China became the fifth nation to launch its own satellite.
• April 25. On this day in 1990, the Hubble Space Telescope was deployed. It is still working extremely well 23 years later. It will probably keep working at peak efficiency for another two to three years. It has taken nearly a half-million photographs of all kinds of incredible celestial objects, and vastly expanded our knowledge of the universe and its processes. Full moon is at 3:57 p.m. This is also known as the Pink, Grass, Fish or Egg Moon.
• April 28. Jan Oort was born on this day in 1900. The Oort cloud, which extends way out beyond Pluto from 5,000 to 100,000 a.u., is the source of most of our comets. By comparison, the Kuiper Belt, which consists of Pluto and hundreds of thousands of similar objects, only extends from about 30 to 50 a.u. from the sun.
Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.