Friday, December 18, 2020

Jupiter and Saturn Offer 2020
Explanation for Brightness
of the 'Christmas Star'

Brian Lada, AccuWeather meteorologist and staff writer;
Educationally Inform, Courtesy AccuWeather News

Dec. 21 marks the official start to astronomical winter in the Northern Hemisphere, which features the shortest day and the longest night - - and the longest night of 2020 will kick off with a rare planetary event that is perfect for folks with a telescope.

Jupiter and Saturn have been prominent features in the night sky all year long, but shortly after the first sunset of winter, the pair will join forces to shine incredibly bright for just a few fleeting hours.

“The two giant planets will appear just a 10th of a degree apart – that's about the thickness of a dime held at arm's length,” NASA explained.

The two largest planets in the solar system will look more like a single bright star in the southwestern sky after sunset on the solstice, an event known to astronomers as a great conjunction.

Jupiter and Saturn will appear closer and closer to each other every night leading up to the winter solstice. (NASA)

These two planets meet up in the night sky about once every 20 years, but this year’s encounter will be the closest they have been able to be seen in the sky since 1226, according to EarthSky. A similar conjunction took place in 1623, but the planets appeared too close to the sun, making it too difficult for observers to spot.

Although the two will appear side-by-side from the perspective of the Earth, in reality, Jupiter and Saturn will be separated by millions of miles.

This diagram shows the approximate locations of Earth, Jupiter and Saturn in their orbits around the Sun on Dec. 21, 2020. (NASA/Celestia)

Because Jupiter and Saturn will look more like one bright object in the sky, and the fact that it is happening around the holiday season, some are referring to this as the “Christmas Star.”

Some even believe that the “star of Bethlehem” in the story of the Magi could have actually been a great planetary conjunction, Forbes said.

The great conjunction will only be visible for an hour or so after sunset, so people will need to head outside at the first sign of nightfall on Dec. 21. The duo will set in the southwestern sky by around 7 p.m. local time for many areas.


This is the perfect event for telescopes, although Jupiter and Saturn will be easily visible to the unaided eye.

“The two planets and their moons will be visible in the same field of view through binoculars or a small telescope,” NASA said.

“In fact, Saturn will appear as close to Jupiter as some of Jupiter's moons," NASA added. This includes the four largest moons of Jupiter, Callisto, Io, Europa and Ganymede.

This means that it will be possible to see both the famed rings of Saturn and Jupiter’s Great Red Spot at the same time with the right telescope.

View of the 2020 Jupiter-Saturn conjunction to scale. This is how it will appear in a telescope. The western horizon is towards the bottom. Adapted from graphics from Stellarium. (Credit: Rice University)

This is a one-night event, so those who miss the planets glowing together on the solstice will have to wait another 20 years to see Jupiter and Saturn side-by-side, although in 2040 they will not be quite as impressive as 2020’s rendition of the event.

However, unlike the nearly 800-year period between the 1226 and 2020 great conjunctions, long-lived stargazers will only have to wait until March 15, 2080 for the next opportunity to witness a great conjunction of Jupiter and Saturn.

Hours after the planetary duo sets, stargazers across the Northern Hemisphere will be treated with a minor meteor shower to conclude the first night of winter.

The Ursids are forecast to peak late Monday night into the early hours of Tuesday morning, but will not be nearly as impressive as the recent Geminids. Only around 5 to 10 meteors per hour will be visible but has occasionally had outbursts of around 25 meteors per hour, according to the American Meteor Society.

No comments:

Post a Comment

Genuine commenting is warmly welcomed--Advertising is not welcome in the Comment Section and will be removed without further explanation.