What is Christmas Star? Here's how to watch Saturn and Jupiter's epic conjunction taking place after 400 years
After 400 years, Jupiter and Saturn are set to appear the closest to each other in the sky on December 21. The great astronomical event is known as ‘great conjunction’ and popularly termed as the ‘Christmas Star’.
NASA Astronomer Henry Throop has stated that the astronomical occurrence "should be visible to almost anyone in the US with a clear view of the horizon". The two planets will seem to come so close that it may look like they are touching, separated by one-fifth the diameter of a full moon. Henry Throop further stated, "They’re not close in space — they’re still hundreds of millions of kilometers apart from each other." He added, "But… they appear as two points very close in the sky… in fact they’re so close that if you extend your pinky at arms length you’ll be able to cover both planets with just your pinky finger."
Usually, when celestial bodies come closer, the event is usually referred to as ‘conjunctions’. But since this astronomical phenomenon is occurring after 400 years, the event has been termed as the "great junction". As the celestial event is taking place on the week of Christmas, it has been popularly named as the ‘Christmas Star’. Throughout the last week of December, the two planets will appear to be very close on the post-sunset night sky. On December 21, the two planets may look like a single bright star to the naked eye.
When and where to watch it?
‘Christmas star’ will appear in the southwestern sky on December 21, 2020, and is likely to be spotted low to the horizon. The planets will sink below the horizon within two hours of sunset, so the great conjunction can be only witnessed for a short while. To witness the great phenomenon, find out your local sunset time here and keep an eye out for about 45 minutes after sunset to the southwest horizon.
Henry Throop said, "In order to find the planets in the sky, it’s really easy if you just look up. If you can see the sunset – that means you are looking to the west, the southwest if you are in the northern hemisphere – then you’ll be able to see Saturn and Jupiter. You want to go outside maybe 45 minutes after sunset. Let the sky darken a little bit. You don’t have to wait until night time. And then look toward the sunset. You’ll have about an hour of time where you can observe Saturn and Jupiter.”
Throop further stated that the phenomenon can be witnessed even from the light-filled cities and will come out great in photographs as well. Throop added, "Anybody can go out and see these planets." If you are planning to photograph the event, here’s the guide for you.
According to a report, the last time Jupiter and Saturn appeared this close was on March 4, 1226. There was another close conjunction between the two planets 400 years back which wasn’t visible to most of Earth, according to Space.com.
To know more about the Great Conjunction, watch this NASA video.