July 19, 2020 – Great Comets

2019 and 2020 have been blessed with the presence of numerous comets.  You might ask, WHERE?!  Me too.  Unless you have a telescope at least 8” in diameter they are just dim smudges and even in an 8” they aren’t anything to brag about.  You need to go bigger, or take long exposure images, or mate a specially designed video camera with your telescope.  That last option outputs to a display so you can comfortably look.  Oh, and the output is bright and even colorful!

Recent comets have been a challenge.  Well, there’s a new comet in town. Comet NEOWISE, aka C/2020 F3 survived a close encounter with the Sun and is heading toward closest approach to us.  Don’t get overly amped up, this one probably won’t be a great comet.  But it might be a good comet.

Great comets are transformative.  They astonish, incite wonder, even fear, and make us consider the larger picture.  They get big, bright, and have marvelous tails. Let’s look at some.

Comet Halley was first documented in the winter of BC 373-372 by Greek historian Ephorus.  It has been followed ever since but hasn’t always been a great comet.  Remember 1986?  It was not great.  Its apparition in 12 BC was considered both an omen of death (Roman general Marcus Agrippa) and possibly birth (the Star of Bethlehem?).  With a period of 74-79 years its return often rekindles prophecy or omens, including in 1066 when Harold II died in the battle of Hastings.  Halley has had 5 great apparitions.

Donati’s Comet (Giovanni Battista Donati) of 1858 was the brightest comet of the 19th century and considered one of the most beautiful ever.  Abraham Lincoln observed it on September 14th, 1858, the night before his third debate with Stephen Douglas.  He described it as “a fire of remarkable whiteness…a distinct disc of brilliant white light…terminating in a broad brush of faint light”. Was it a good omen?

The Great Daylight Comet of 1910 snuck up on everyone that January.  It apparently brightened suddenly because it was not discovered until already visible with the naked eye.  This comet became brighter than Venus.  It was also a big surprise because everyone was waiting for the next apparition of Halley’s Comet in April, which itself was great. A twofer!

Comet Ikeya-Seki (1965) is a Sun-grazing comet, and got within 300,000 miles from the Sun. It became one of the brightest comets of the past 1000 years.

Hyped Kohoutek (1973) …disintegrated and fizzled. Not great.

Comets Hyakutake (1996), and Hale-Bopp (1997) were treats to cap the 20th century.  They were both bright, beautiful, and big and stayed a while.  They were great comets.

What’s in the Sky?

July 17; 30 minutes before sunrise; east:  A crescent Moon, Venus, and Aldebaran grace the sky

Comet C/2020 F3 (NEOWISE): About an hour after sunset; northwest:  Scan between the horizon and the Big Dipper’s cup.  Its tail points up. Binoculars help.