Just after sunset on the evening of Dec. 21, Jupiter and Saturn will appear closer together in Earth's night sky than they have been since the Middle Ages, offering people the world over a celestial treat to ring in the winter solstice.

"Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to one another," said Rice University astronomer Patrick Hartigan. "You'd have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky."

Jupiter and Saturn have been approaching one another in Earth's sky since the summer. From Dec. 16-25, the two will be separated by less than the diameter of a full moon.

"On the evening of closest approach on Dec 21 they will look like a double planet, separated by only 1/5th the diameter of the full moon," said Hartigan, a professor of physics and astronomy. "For most telescope viewers, each planet and several of their largest moons will be visible in the same field of view that evening."

Though the best viewing conditions will be near the equator, the event will be observable anywhere on Earth, weather-permitting. Hartigan said the planetary duo will appear low in the western sky for about an hour after sunset each evening.

"The further north a viewer is, the less time they'll have to catch a glimpse of the conjunction before the planets sink below the horizon," he said. Fortunately, the planets will be bright enough to be viewed in twilight, which may be the best time for many U.S. viewers to observe the conjunction.

"By the time skies are fully dark in Houston, for example, the conjunction will be just 9 degrees above the horizon," Hartigan said. "Viewing that would be manageable if the weather cooperates and you have an unobstructed view to the southwest."

But an hour after sunset, people looking skyward in New York or London will find the planets even closer to the horizon, about 7.5 degrees and 5.3 degrees respectively. Viewers there, and in similar latitudes, would do well to catch a glimpse of the rare astronomical sight as soon after sunset as possible, he said.

Those who prefer to wait and see Jupiter and Saturn this close together and higher in the night sky will need to stick around until March 15, 2080, Hartigan said. After that, the pair won't make such an appearance until sometime after the year 2400.

Related Links
Rice University
Stellar Chemistry, The Universe And All Within It

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Shape-shifting mirror hunts for exoplanets
Muenster, Germany (SPX) Nov 16, 2020
This Muenster bendable space mirror can have its shape shifted to compensate for manufacturing or alignment errors within orbital telescopes or temperature-driven distortions. Very large space telescopes are necessary to increase image resolution and sensitivity, whether for deep space exoplanet detection or sharpened views of the terrestrial environment. But large instruments will be harder to align and more sensitive to the absence of gravity and the environmental extremes of space. Being able t ... read more