Evan Hazard/Northland Stargazing: A comet some of us may have seen, and a nearby red giant
Algol is too low in the northwest at dusk to observe its minima. If you’re up in the wee hours and want to know its minima, go online to www.nightskyinfo.com/sky_ highlights/ algol, a site giving the minima in 24-hour mode, where 1911 7 p.m. and in UT (Greenwich Standard Time). Subtract 5 hours to get CDT.
Jupiter, our one bright evening planet, is slowly moving down toward the west/northwest horizon. Thursday Venus was precisely on the far side of Sol. By April’s end, it will be visible just above the west/northwest horizon shortly after sunset. April 18 (Patriots’ Day in MA), Mars will also be precisely on Sol’s far side. It will be an early morning summer object.
Saturn is at its brightest, reaching opposition (opposite Sol’s position in the sky) April 28. Being opposite Sol, it will be up all night, rising at sunset and setting at sunrise. Mercury is too close to the sunset to be seen; it will be precisely on the far side of Sol May 11.
I’m writing this on March 11, so cannot comment on Comet PanSTARRS, which should have passed night-by-night above the horizon from west to northeast from March 12 to early April, getting dimmer as it moves away from its rendezvous with Sol. It was a decent comet for Australians, Argentineans, Tanzanians, and such. I expect to be in the Cities from about March 14-20, which won’t help any. Here I can get to dark western skies in a few miles; not down there. I hope some of you got a good look at it. After sundown this evening the sky was quite clear here, except for a cloud bank extending across the western horizon.
April’s “Sky & Telescope” has an article about Comet Kohoutek, astronomical flop of the 20th century. It notes that astronomer Fred Whipple wrote in the magazine in ‘74, “If you must bet, bet on a horse, not on a comet.” As a slightly staunch Methodist, I’d recommend neither.
Orion, Taurus, Perseus, and other winter friends are leaving us. It’s astronomical spring, and Virgo (with bright Spica), Boötes (with even brighter Arcturus), Corona Borealis, and Hercules are all well up in the east.
Why is Arcturus so bright? Partly because it is relatively close, only some 37 light years away. It is probably a bit more massive that Sol, and, at an age of some 7 billion years, has fused most of the hydrogen in its core, and is therefore fusing helium into carbon. The increased heat has caused it to become a red giant, giving off much more energy than Sol. It is not big enough to become a neutron star, but will ultimately collapse to become an inconspicuous white dwarf, as Sol will also in another 5 billion years or so. Don’t lose sleep over it.
Evan Hazard also writes “Threescore and Ten” for The Pioneer’s “Prime Time.”