StarWatch: Moravian College Astronomy

StarWatch for the greater Lehigh Valley

MARCH 2014

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

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

Current Solar X-rays:

Current Geomagnetic Field:

915 MARCH 2, 2014: Rigel: Blue Jewel of Orion: The winter constellations are some of the finest that you will encounter, and with the icon of the season, Orion the Hunter, due south after dark, its stars beg investigation. There is no other pattern that has as many blue giant stars in it, and the best of them all is Rigel, not just a giant, but a blue supergiant. Rigel, “rijl al-jauza,” Arabic for the foot of the “Central One,” can be found as the blue-white scintillating diamond beneath Orion’s three straight belt stars. It is the brightest luminary of the constellation, but listed as the Hunter’s beta star, opposite to red Betelgeuse with the three belt stars in between. What makes Rigel so special? Put it in the center of our solar system, and this star would extend to nearly the orbit of Mercury. Rigel is a staggering 63 million miles in diameter and produces the energy of 85,000 suns. We’d simply be “toast” in a second or two. Thank goodness, it lies at a respectable distance of 860 light years; that’s traveling at 186,000 miles per second for all of the seconds contained within that time span. Unlike our much slower paced sun which will be around for at least 10 billion years, stars like Rigel measure their lives in millions of years. In fact, at an estimated age of 10 million years, Rigel is definitely feeling the pangs of old age rapidly creeping upon itself. Astronomers, however, are still unsure of Rigel’s eventual fate. Will it become a red supergiant and ultimately detonate in a spectacular supernova event, brightening to the luminescence of the quarter moon, or has Rigel already seen its red giant days, and now has contracted back into a more compact, hotter star. If we knew its mass, the problem would be solvable, but even though Rigel has its share of companion stars, four in total, their great distances have made it impossible to glean any orbits, even from the closest one. Still shrouded in mystery, Rigel remains one of the jewels of the heavens. See if for yourself tonight!

916 MARCH 9, 2014: Betelgeuse: Do Not Resuscitate: If any star were eligible for assisted living or a DNR (Do Not Resuscitate) order, the bright red supergiant, Betelgeuse, Orion the Hunter’s shoulder star (left side as we view him) should be standing first in line. Luminaries like Betelgeuse live fast and die young in comparison to slower-paced stars like our sun. Within a matter of millions of years, these massive stars rip though their hydrogen fuel supplies, creating huge reservoirs of helium in their innermost core, massive enough to compress and heat to temperatures of 180 million degrees F., where helium spontaneously begins to fuse into heavier carbon and oxygen. That’s where astronomers think Betelgeuse sits right now. Everything about Betelgeuse is ginormous. It’s a star that conservatively stretches outward twice the distance of Mars’ orbit around the sun. This means that at the Earth-sun distance of 93 million miles, we would be found in the innermost four percent of the star. At its largest width, Betelgeuse may extend to Jupiter’s orbit, putting Earth within its deepest one percent. Then there is this behemoth’s energy output which depending upon what distance is chosen (495-640 light years) ranges from 65 to 105 thousand times the energy production of our sun. All of these factors point to a “lifestyle” that puts Betelgeuse on the verge of catastrophe, on the brink of becoming a supernova that would blast itself to the brightness of a nearly full moon, but emanate from a starlike point in the heavens. Supernova Betelgeuse would be easily seen in the daytime, cast sharp, distinctive shadows by night, and would be dangerous to view through telescopes and binoculars. As Ed Guinan, of Villanova (PA) University has put it, Betelgeuse is so close to self-destruction that it may have already happened and its light is screaming towards us, ready to be witnessed in the next few centuries, or maybe even tomorrow.

917 MARCH 16, 2014: Dissecting Orion's Sword: Orion the Hunter continues to be center stage in the south right after darkness, but it will not be there for long. The rapidly increasing light of spring and Orion’s daily westward motion, due to Earth revolution around the sun, will squeeze it from visibility in the evening sky in just one more month. Look for Orion’s three belt stars, top to bottom—Mintaka, Alnilam, and Alnitak, mid-sky and just a little to the west of south. Beneath his belt is Orion’s more elusive sword, which appears to the unaided eye from suburban locales as three fainter stars, but when viewed through binoculars or small telescopes, resolve themselves into star clusters and nebulae. By far, the most famous is the Orion Nebula (M42), 24 light years in diameter and 1,350 light years distant. It is a birthing place for stars. Its Trapezium cluster contains five 15-40 solar mass stars visible through small telescopes, but Theta1 C Orionis, containing 40 times more hydrogen than our sun, is the standout, in binoculars. Its “surface” temperature exceeds 80,000 degrees F., and its luminosity equals 250,000 suns. It is destined to supernova in about one million years. Just above the Orion Nebula is M43, structurally tied to M42, but separated by a dark lane of dust. Target this area with a telescope. The Running Man, NGC 1977, a small cluster of related stars forms the top of Orion’s sword to the unaided eye. Through binoculars three tightly packed luminaries can be seen with an additional star above and to the right. Photography reveals a beautiful blue reflection nebula associated with the dust through which the brightest star, 42 Orionis, is shining. Below the sword lies Iota Orionis, a naked eye star, which is associated with a very faint nebulosity, NGC 1980, not easily seen even through large telescopes. All of this and more lies easily within one binocular field of view in your evening sky tonight.

918 MARCH 23, 2014: April 15: Lunar Eclipse Game Time: Tax day, April 15; don’t you just love it? Here is a small incentive to get your forms completed and filed in advance. During the early morning hours of Tuesday, April 15, Europe and the Americas are treated to a total lunar eclipse. The moon will be full and precisely opposite to the sun. Since the Earth produces a shadow of 750,000 miles in length, and the moon orbits about a quarter million miles from us, when Luna is exactly opposite to the sun, it MUST pass through the Earth’s shadow. The beauty of a lunar eclipse is that anyone on the nighttime hemisphere of the Earth and under the dome of a clear sky has a grandstand seat. That puts nearly three billion people in the stadium to watch the eclipse. Kickoff begins at 1:58 a.m. EDT when the moon first makes contact with Earth’s shadow. For CDT, MDT, and PDT zones simply subtract one, two, or three hours respectively to get the correct time. During the next hour and eight minutes, the moon trudges ever deeper into the umbra (shadow) until at 3:06 a.m. EDT, it is completely immersed. That’s the start of totality or second contact and really the most exciting segment of any lunar eclipse. The moon takes on a variety of hues—browns, reds, oranges, and even yellows, but sometimes when the air is dusty after a major volcanic eruption, the moon simply disappears. Presently, the atmosphere is clear so this will probably be a bright and colorful eclipse. The moon will spend one hour, 20 minutes in Earth’s shadow and begin to emerge at 4:26 a.m. EDT (third contact). The moon treks from the shadow during the next hour, eight minutes, leaving Earth’s umbra (fourth contact) by 5:34 a.m., EDT with a healthy twilight in the eastern sky, and with the moon only eight degrees above the western horizon on the East Coast. The game is free and the halftime activities colorful. The stadium holds billions, and if you plan ahead, your taxes will be completed. It’s the best astronomical show of the year!

919 MARCH 30, 2014: Watching a Total Lunar Eclipse: April 15 holds the promise of a really impressive light show during the early morning hours of tax day as the full moon encounters the Earth’s shadow and hides for awhile in its darkness. I have to admit that the scheduling of this event between 1:58 and 5:34 a.m. EDT is going to put a real crimp in my ability to be coherent for my Tuesday evening astronomy class, but hey, even that shall pass. Total lunar eclipses are the less spectacular of the two eclipse families. By far, total solar eclipses, where the moon hides the sun, are truthfully the crème de la crème of astronomical events. August 21, 2017 is the next total solar eclipse visible from the US, but most people will have to travel to see it. Day will literally change into night within 10 to 15 seconds. Sol, will look like a brilliant diamond ring just before totality, and then when totality begins, the wispy corona of the eclipsed sun will encircle the dark moon while planets and bright stars become visible right before your very eyes. However, the biggest perk of a total lunar eclipse is that more than half of the world gets to view it. About 30 minutes before first contact around 1:30 a.m., as the moon pushes deeper into Earth’s secondary shadow, the area of the moon closest to the true shadow will start to become dusky in appearance. An astronaut stationed on the moon in this grayish area, with filters protecting his or her eyes, would watch the Earth slowly eclipsing the sun. As more and more of the Earth covered the sun, the sun’s light in that region of the moon would have to be lessened, and it would appear from Earth to be diminished in brightness. These are merely the preliminary aspects to the beauty that lies ahead. At 1:58 a.m., EDT the limb of the moon closest to the umbra makes first contact with the shadow and within a minute, the human eye can detect it beginning to sweep across the lunar surface. More next week about the visual aspects of the April 15 total lunar eclipse.

[March Star Map]

[March Moon Phase Calendar]