The Great Conjunction of Jupiter and Saturn - Dec 21st, 2020

We will witness a very rare and beautiful spectacle in the coming days. On December 21st, Jupiter and Saturn will be less than one-tenth of a degree apart from each other as seen from Earth, a rare alignment that happens only every 400 years at this extremely close separation. 

The Great Conjunction

Great Conjunction: Conjunctions occur often in the heavens, as heavenly bodies pass near each other, on in the less common scenario where the Moon covers stars and occasionally planets, and as planets and asteroids cover stars. In any case, a conjunction is usually a fascinating thing to see, particularly up close if you have binoculars or a telescope. When Jupiter and Saturn pass near each other every 20 years, we have a 'Great Conjunction' in which the two massive planets are very near each other. But every 400 years, the alignment is extremely good and we have both objects in one telescopic field of view, as portrayed in the image to the right. 

How to See It: The two planets will be visible only for a short while after sunset, and you will need a clear view to the west to see this. Look directly to the southwest of the point of sunset an hour after the sun goes down. If you have a telescope or binoculars, this is definitely the time to get them out and put them to work. If you can, look for the pair on Saturday 19th or Sunday 20th to get an idea where to find them. They will be in roughly the same place on the 21st, but through the telescope or binoculars the difference from one night to the next will be dramatic. 

Learn More: There are excellent articles online if you want to learn more about this rare and exciting event, on Scientific American or Earth-Sky. I find all of the detailed planetary geometry fascinating, and fun to understand how such alignments occur and can be accurately predicted. 

I wish you clear skies and happy viewing! 

Image courtesy Earth-Sky. 

Geminid Meteor Shower 2020

The Geminid Meteor Shower peaks on Sunday 13th and Monday 14th. This year, it will be especially well timed with the New Moon, meaning that there will be no moonlight to brighten the sky, leaving the sky dark and at its finest for a meteor shower. 

Fireball

What causes a meteor shower? Every day, there are dust particles and small objects flying into the Earth's atmosphere from space, sometimes randomly, sometimes predictably, causing a 'shooting star' in the night sky. And sometimes with great surprise, a larger piece of an asteroid will fly into the atmosphere and become visible as a Fireball, as was the case two weeks ago in Japan. The Geminids are predictable, one of many annual meteor showers that are caused when the Earth travels through the remnants of a comet or asteroid that has orbited the Sun sometime in the past, leaving a debris stream in its wake. 

What causes the Geminids? Every year on December 13th and 14th, the Earth travels through such a wake (of an asteroid named 3200 Phaethon) and we have a lovely meteor shower, as the dust and sand particles impact the Earth's atmosphere at high speed and heat up the air, causing it to glow as the meteor hurtles toward Earth. Nearly all of the particles in a meteor shower never reach the surface of the Earth, but those that do (called Meteorites, once they've landed) are of great scientific interest. 

How to see the Geminids: For any meteor shower, you want to find a dark location where you have a wide horizon. You don't need to look in any one direction, but ideally relax on a blanket or chair and simply look up, and have patience. And of course, for most of us it's winter and it's cold, so you need to dress extra-warm. 

If you want to learn more, this helpful article from Astronomy Magazine provides a great deal of information about the Geminids. 

Happy Viewing, and stay warm! 

Image courtesy of ESO.