It's the shortest day of the year, and while only 10 hours of daylight may not seem like the greatest thing these days, there is one bright spot, literally.
Around 6:30 p.m. tonight, Houstonians will be able to walk outside and look up to the southwest sky and see something that hasn't been visible since the 1600s. Look for the brightest object up there, besides the moon, says Eric Berger of Space City Weather. That's Jupiter and Saturn (which will look slightly fainter) crossing paths. Although the two planets, the largest in our solar system, are actually 456 million miles apart, they will appear so close together that one pinkie held at arms length will be able to cover them both tonight, according to NASA.
“You can imagine the solar system to be a racetrack, with each of the planets as a runner in their own lane and the Earth toward the center of the stadium,” said Henry Throop, astronomer in the Planetary Science Division at NASA, in a statement. “From our vantage point, we’ll be able to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21.”
This "Christmas Star" will be the closest these two planets have been to each other in almost 400 years—the "Great Conjunction" was recorded in 1623, according to NASA, and it's been 800 years since it's happened at night. (The last time it happened at night was around 1226, when Gengis Khan was prowling Asia.)
“Conjunctions like this could happen on any day of the year, depending on where the planets are in their orbits,” said Throop. “The date of the conjunction is determined by the positions of Jupiter, Saturn, and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis. The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system.”
So, go outside and look up, Houston. If the weather cooperates, there's going to be a sight to see tonight and for the next few nights leading up to Christmas. It won't be happening again until 2080, so enjoy it.