by William J. Bechaver
Orion is perhaps the most recognizable and easily identifiable constellation in our night sky.
It is certainly the most distinct star formation in our winter skies, visible almost any time of the night, and all night, and from virtually every location on Earth.
For millennia the three stars almost equally spaced and nearly in a straight line, have been identified as the Hunter’s Belt.
The other most distinct star in the constellation is Betelgeuse, the armpit of Orion, not only because of its dominant brightness, but also for its prominent red color.
And yet, over the past few months, Betelgeuse has begun to dim noticably. The cause of the rapid dimming has been the focus of much speculation amongst the scientific community.
Betelgeuse is a red supergiant, a star so massive that it is 700 million times the volume of our own Sun. In fact, if you were to put Betelgeuse into the center of our solar system, it would completely consume all of the inner planets, out beyond the orbit of Mars, most of the asteroid belt, almost to the orbit of Jupiter.
It appears so bright because it is a mere 642 light years from our own solar system. That means, it takes the light an amazing 642 years to reach Earth from Betelgeuse. But being so massive, that’s why it still shines so prominently in our night sky.
Until recently, Betelgeuse was generally considered the tenth brightest star in our night sky. Now, with its recent dimming, it is currently not even in the top twenty!
Red supergiant stars live fast, burning up tremendous amounts of energy at one time. As a result, they usually have short lives, compared to smaller yellow stars such as our own Sun.
During their lifetimes, red giants expand as they burn up their fuel. When their fuel it almost completely expended, they begin to dim, and as they slowly die, a red giant will begin to collapse in upon itself, a victim of its own immense gravity.
As it collapses, ultimately its mass will explode in a blinding flash of light, known as a supernova. Following such a cataclysm, the star will be no more, leaving behind only the remnants of gases and dust.
Is the dimming we’ve witnessed recently in Betelgeuse a foreshadowing of the end of its life? Is it burning out, about to collapse, and become a supernova?
If so, at only 642 light years distant, it would be the brightest supernova ever witnessed from Earth in the history of mankind.
The brightest supernova ever witnessed from Earth in recorded history was way back in 1054, by Chinese astronomers, in the constellation Taurus. But it was at the astounding distance of 6,523 light years away, greater than ten times more distant than is Betelgeuse. What was left behind was what is now identified as the Crab Nebula, a gaseous cloud of dust and debris, which is a supernova remnant.
So if the dimming of Betelgeuse is a precursor of its demise, we could see the brightest supernova ever witnessed by mankind. And it could happen tomorrow!
Though scientists deem that unlikely, it is also not impossible. Of course, if it happened 642 years ago, we would see it tomorrow, for it would take the light from the event that long to reach Earth. If the supergiant actually went supernova tomorrow, we would not know it, or even see it from Earth, for another 642 years.
Scientists warn that there could be other causes for the dimming of Betelgeuse. It has always been a variable star, its luminance pulsing brighter and dimmer on a regular basis.
Of course, the fluctuation and dimming of the star has never been witnessed to such a dramatic degree, over such a short period of time, leading some to believe a significant event could be imminent.
But the dimming could also be the result of an outpouring of gasses and matter, which are simply coming between the star and us, simply blocking some of the light to be obscured behind a massive dust cloud.
If it were to happen in the coming weeks or months, it would be a spectacular sight to behold. It would shine so brilliantly, it would completely obscure the other stars in Orion for a considerable amount of time.
If it happens during the summer months, when Orion is generally not visible in our night skies, we would still be able to see it. It would shine so brightly that it would easily be visible in the daytime sky as well.
It would shine for a time more brightly than the full moon, and remain about ten times brighter than Venus.
How long the spectacle of the supernova will last is also hard to predict. But it is expected that it would shine brightly in our sky for several months, slowly dimming until then, it would be seen by the naked eye no more.
It would result in another astounding change. Not only would there be another bright body shining in our day and night skies for several months, but then when it finally does fade from view, Betelgeuse will be no more, and the constellation of Orion will be forever altered, lacking one of its most recognizable and distinctly beloved features.
In its place would be another supernova remnant, only visible through telescopes where once the mighty giant had roamed.
Simply, we don’t know what is causing the sudden dimming of Betelgeuse. Scientists do agree that the massive star will one day supernova. It could be tomorrow, or it could be in 100,000 years. The fact that the event will happen is undisputable. Unfortunately, the timeline for such an occurrence is a little harder to predict and pin down.
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Astronomical Times And Distances of naked-eye objects for this weekend.
Sun Set = 5:20 p.m.
9 minute later than last week
91.59 million miles from Earth
79,467 miles further than last week
Mercury Set = 6:32 p.m.
34 minutes later than last week
108.73 million miles from Earth
12,114,075 miles nearer than last week
Venus Set = 8:40 p.m.
15 minutes later than last week
100.65 million miles from Earth
4,251,677 miles nearer than last week
Moon Set = 12:50 a.m.
6 hours 46 minutes later than last week
246,792 miles from Earth
789 miles nearer than last week
Mars Rise = 3:45 a.m.
5 minutes earlier than last week
179.91 million miles from Earth
5,166,725 miles nearer than last week
Jupiter Rise = 5:26 a.m.
21 minutes earlier than last week
562.75 million miles from Earth
4,800,702 miles nearer than last week
Saturn Rise = 6:08 a.m.
24 minutes earlier than last week
1.01 billion miles from Earth or
1,019.15 million miles from Earth
2,805,963 miles nearer than last week
Sun Rise = 7:04 a.m.
6 minutes earlier than last week
91.59 million miles from Earth
80,034 miles further than last week
7,250 miles further than last night
First Quarter Moon occurs on Saturday, February 1st, at 6:41 p.m.
Note: Times are local Mountain Time. Actual sundown is about ten minutes earlier than calculated sunset. Along the front range, differing times may vary depending on your distance from the mountains.
• · William J. Bechaver is the director of SPACE • Spanish Peaks Amateur Cosmos Enthusiasts, the premier Astronomical Society for Southern Colorado and Northern New Mexico.
The planets and their relative positions in the solar system for this weekend.–
–Planet sizes and distances are obviously not to scale.