Celestial News: Keep an eye on Betelgeuse
For Steamboat Pilot & Today
Stars seem like eternal beacons that will shine forever. They return every night in the same centuries-old patterns in our sky. But, the stars are not as constant as they seem. The lives of stars, even the ones that burn fast and furious, are measured in millions of years. A single human lifetime is not enough time to notice a difference in most stars.
There are exceptions, however. Some stars, in the latter stages of their lives, begin to pulsate, changing their brightness over a period of days, weeks or months. These are the variable stars.
One such variable star is the bright red star Betelgeuse, marking the shoulder of the familiar winter star pattern of Orion, the Hunter. Its variability has been known and studied for centuries. According to the American Association of Variable Star Observers, Betelgeuse, at its brightest, can rival or even outshine Orion’s other bright star Rigel, marking the Hunter’s foot. NASA lists Betelgeuse as the 10th brightest star in our night sky, but, because of its variability, it can shine as our sixth brightest star or drop out of the top 20 altogether.
Last month, astronomers noticed Betelgeuse had faded much more than usual. In fact, according to the Variable Star Observers records dating back to 1893, this is the faintest it has been in over a century of observations. What’s up with Betelgeuse?
Well, probably nothing. It is most likely experiencing a super minimum as two of its variability cycles sync up and reach minimum brightness at the same time. Astronomers expect a little more dimming before the star begins to rebound in brightness later in January.
On the other hand, stars like Betelgeuse are well advanced in age and are destined to explode as supernovas at the end of their lives. Astronomers have long considered Betelgeuse as the best nearby supernova candidate, at a distance of about 640 light years. When an astronomer says that Betelgeuse can explode “at any time,” that means “any time within the next 100,000 years.” That’s quite a hedge on their bet.
There hasn’t been a bright supernova in our Milky Way galaxy since the supernova of 1604. Kepler, Galileo and others witnessed this event, but without the benefit of a telescope. No nearby supernova has been scrutinized with modern telescopes and instruments. Sure, we’ve seen supernovas in galaxies far, far away, but none have been seen close to home.
So, there is some excitement in the astronomical community, warranted or not, that Betelgeuse might be ready to pop. Astrophysicists theorize that a pronounced fading might presage an impending supernova explosion. If Betelgeuse continues to fade into January and beyond, then look out — the end might be near.
What would it look like from planet Earth, if Betelgeuse were to explode as a supernova? It would probably shine more brightly than the full moon in our sky, casting distinct shadows at night and be visible in broad daylight for several months until it faded into obscurity. The outline of Orion would be forever changed, missing the familiar bright red star on his shoulder.
Step outside tonight and peer up at our old friend Orion. He’s rising up in the eastern sky after sunset. Betelgeuse is the star on Orion’s right shoulder on the left side as we view him. Compare it to Rigel and you can see for yourself that Betelgeuse has diminished noticeably in brightness. Will it return to its original prominence in the weeks ahead, or is it destined to make history as the first supernova in over 400 years? Keep an eye on Betelgeuse.
Finally, I’d like to share with you a poem written decades ago by my friend and colleague and former poet laureate of the State of Georgia, the late Bettie Sellers. She and I taught together at Young Harris College in the mountains of north Georgia, back in the ’70s, ’80s and ’90s. It’s called “Complaint to Betelgeuse,” and it’s always been one of my favorites.
“Complaint to Betelgeuse”
by Bettie Sellers
I used to know that stars were stars
and stayed wherever in that space
their ordered orbit was. The sky
was snug with Cassiopeia’s Chair,
and night had Big and Little Bears to hunt.
Then, winking moving lights began to stitch
an arch from Sunset Ridge to Raven Cliffs –
planes to Birmingham and points beyond
with travelers drowsing past sleeping hills
folded like dark velvet, with ribbons wound
for lake and stream, silver in reflected light.
Now, satellites invade the ridge –
the star I thought was Venus rising
keeps on rising out of sight
to bring the morning’s news – and wars
are instantaneously played on beams
that tear Orion’s belt, divide Andromeda.
Jimmy Westlake’s column appears monthly in Steamboat Pilot & Today. Check out Westlake’s 2020 Cosmic Calendar of sky events at jwestlake.com.
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