StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

JANUARY 2016

JANUARY STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 9 p.m. EST: NORTH | EAST | SOUTH | WEST | ZENITH

Current Solar X-rays:

Current Geomagnetic Field:

1011 JANUARY 3, 2016: Eying Aldebaran: Turn right at Orion the Hunter. That’s the constellation which is in the SSE at 9 p.m. with its triad of bright belt stars, sometimes called the Three Maries, stationed in a neat tidy row. Follow these stars upward like a rocket launcher, and you will pass just below an orangey luminary named Aldebaran, the alpha star and bright eye of Taurus the Bull. Aldebaran is about 65 light years distant. This means that the energy being viewed early in 2016 left Aldebaran shortly after the New Year in 1951 and has been traveling towards us at the breakneck speed of 186,282 miles per second ever since. Aldebaran is a red giant, 425 times more luminous than our sun, and if placed in our solar system, it would stretch halfway to Mercury and appear large enough to cover easily the seven main stars of Orion the Hunter. Aldebaran is close to the end of its life, with a thin shell of hydrogen gas furiously fusing into helium around an inert helium core. As the core gathers up more helium from the hydrogen “burning” shell, it will continue to contract and heat, causing the shell burning to accelerate and Aldebaran to nearly double in brightness, increase in size, and redden even more. Using binoculars reveals that Aldebaran is also the brightest star of a V-shaped grouping that forms the head of Taurus the Bull. If Aldebaran is deleted from the “V,” the remaining luminaries are all part of an open cluster of stars called the Hyades, located about 150 light years from the sun and which formed about 650 million years ago. It is in open clusters that star births take place today, but unlike the Hyades, most clusters dissipate (evaporate) after a few hundred million years, member stars going their separate ways because the gravitational attractions among constituents are not strong enough to hold the system together. Our sun was born about 4.5 billion years ago in an unknown cluster which has since evaporated, and this will also be the probable fate of the Hyades cluster in the distant future.

1012 JANUARY 10, 2016: Sisters All Aglow in the Frosty Night: We had several clear, chilly nights last week, and on the coldest evening, January 4, I had a telescope in the front yard to view the early winter scenery. One of the hallmarks of late fall and winter is the Pleiades or Seven Sisters, a wispy, gossamer cluster of stars that looks like a small exhalation of breath against the frosty night. If you trace the three belt stars of Orion up and to the right, you’ll pass orangey Aldebaran (last week’s StarWatch), and continue in the same direction to intersect the Seven Sisters. Looking at them with averted vision, the glow will seem to pop, and you’ll probably be able to observe half a dozen stars or so. That’s because you’re looking at the cluster with the rods of your eyes which are more sensitive to light, but less to color and visual acuity. The Pleiades are similar to the Orion Nebula, only 100 million years into the future, a grouping still in its infancy compared to the sun. There are over 1000 members, but it’s the 14 young, hot blue stars that cause the Sisters to be visible against the velvety night. Because the cluster is close to us, it appears huge, about three lunar diameters across. That makes it difficult to view in its entirety through most telescopes, but the Sisters become one of the most cherished targets to observe through binoculars. If you view them, know that the photons of light entering your eyes departed from the Pleiades about the same time that Hans Lippershey (1608) invented the telescope, and Galileo Galilei first observed and sketched them (1609-10). To the left of the Pleiades is Auriga the Charioteer, with white Capella about 42 light years in distance, the sixth brightest luminary of the night. Stars, like Capella and our own sun, were born in clusters like the Orion Nebula and the Pleiades eons ago. Most clusters dissipate with the Pleiades being no exception. In about 250 million years they will have evaporated, their members orbiting solo around the Milky Way just like our sun.

1013 JANUARY 17, 2016: Peekaboo Aldebaran: Two weeks ago, I wrote about the bright, orangey giant star, Aldebaran, which is the steely eye of Taurus the Bull that is keeping an “eye” on Orion the Hunter. If the three belt stars of Orion are followed upward, the first bright luminary encountered will be Aldebaran. Along with Orion, they are essentially due south at 9 p.m. this week. Watch Aldebaran and the moon. Luna begins the week in a modest waxing gibbous phase (growing brighter and more bulbous), nearly 30 degrees to the west of Aldebaran. Early Monday evening will find the moon having moved to within 14.5 degrees of Taurus’ eye, but it will be making a “bull’s eye” with Aldebaran the following evening. If conditions are favorable on Tuesday, go out around 7 p.m., and you’ll observe the moon just over a degree shy of the star. By 8 p.m. this distance will have narrowed to just over one lunar diameter. At 9 p.m., less than a quarter of a degree separates the moon’s limb from covering Aldebaran. Visual acuity and weather conditions may dictate the use of binoculars or a small telescope after this time. The contrast between the two objects created by their differences in brightness will make Aldebaran increasingly harder to view. During the next 30 minutes the moon will appear to overtake the Bull’s eye, covering or occulting Aldebaran at 9:30 p.m. EST. It will be the unlit part of the moon that will make contact with Aldebaran first, and this may create some difficulty in actually witnessing the disappearance. Luna’s unlit limb will not be visible even in telescopes, so continuous vigilance at the eyepiece may be necessary to witness the luminary’s disappearance. Most stars simply wink out because the moon has no atmosphere, but because Aldebaran has a measurable disk, it may rapidly fade over a second or so. About 10:42 p.m. Aldebaran reappears on the sunlit limb of the moon, again requiring watchfulness and a little bit of luck to see it in real time.

1014 JANUARY 24, 2016: Challenger Plus 30: The classroom was packed with kids whose silent stare towards the tube told me that something horrific had happened. The video looped again to the blastoff, the ignition of the huge liquid fuel tank, the buildup of thrust as the Shuttle vibrated to life, swaying ever so gently; then at zero the ignition of the two solid fuel boosters, and liftoff with a slight forward motion. Already commentators were circling a tiny orange flame coming from the right solid fuel booster, which at about 70 seconds became noticeably brighter, and then… We can all see it in our minds. The puffs of white crystallized air created by the escaping and combusting liquid hydrogen and oxygen fuel, and the detached solid fuel boosters arching outwards like the petals of a flower. I knew instantly that there could be no survivors. So what happened? Because basic rules were not adhered to, the Challenger was launched in conditions too cold for the rubber O-rings to function properly. They kept exhaust from escaping between the various sections of the solid fuel boosters. One of the O-rings on the right booster had contracted to the point where it could no longer seal its section, and hot, escaping gasses began to burn through it. The flame severed a strut supporting the booster and penetrated the external liquid hydrogen tank of the main engine. Between the pivoting of the solid fuel booster and the 2.8 million pounds of thrust created by the crumbling hydrogen tank, Challenger lost stability. The oxygen tank became compromised, mixing the two elements, and the Challenger exploded. Space travel is still dangerous, and space is unforgiving when mechanical or human errors occur. That’s why all astronauts must sweat the small stuff, be on top of every detail, and understand all of the components of a mission to insure its success. They are smart, practical, adaptable, and driven, but most of all, they are heroic. Going into space is not like going to work. January 28 marks the 30th anniversary of the Challenger tragedy.

1015 JANUARY 31, 2016: Five Planets on Tap: If you are like me, then you probably think that mornings are overrated. My rising time for nearly five decades was at 5:45 a.m.; thus I can say unequivocally that I’ve seen my share of sunrises and dawn starscapes. It was always a great way to see the evening heavens about six months into the future. When school started, it was the winter constellations that greeted me in my bathrobe and flip-flops when I dashed outdoors for a quick look. By the end of the term, it didn’t matter because the sun was already up when the alarm went off. So for you morning achievers, here is an opportunity to observe all five planets that can be seen with the unaided eye in the dawn sky, particularly if you live in a place with a good SE horizon. The time to be at your observing post should be about 6:30 a.m. If you are too much later, the brightening sky will interfere. Also having binoculars would be handy for Mercury since it sometimes gets lost in the glare of dawn’s light. Start off on Sunday morning, Jan. 31, at 6:30 a.m. Yes, this could be an all week affair. The waning gibbous moon will be to the right of Mars. Much farther to the right in the western sky will be bright Jupiter. You can easily spot Jove before bedtime, low in the east around 10 p.m., and breaking the skeletal treetops an hour later. Jupiter will be the brightest object in the evening sky, so there is no avoiding it. Returning to the dawn sky on Jan. 31, you will notice, just east of south, another bright “star” that will not be twinkling. That will be Saturn. Through a telescope, even at very low magnifications, the ring system will be easy to spot. To the left of Saturn and low in the SE will be brilliant Venus. Nothing can beat its luminescence except the moon and the sun. About eight degrees to the left of Venus, or a fist held at arm’s length and just a little lower, will be Mercury. Here is where binoculars will come in handy. The moon will be on top of Mars on Feb. 1, near Saturn on the 3rd, and between Mercury and Venus on Feb. 6th. Much success and no yawning, please!

[January Star Map]

[January Moon Phase Calendar]