SAN DIEGO (KGTV) — On Monday, a planetary sight unseen for nearly 800 years will captivate stargazers as Jupiter and Saturn create a celestial event known as the "Christmas Star."
The two bright planets will align to create an even brighter display, culminating on the night of Monday, Dec. 21, according to NASA. While the two planets pass each other regularly, this year's event is so rare because not only is the distance between the planets so close but it's also occurring at night.
"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 Headquarters in Washington. "From our vantage point, we’ll be able to be to see Jupiter on the inside lane, approaching Saturn all month and finally overtaking it on December 21."
The closest alignment will last for a few days and appear just a tenth of a degree apart. On Monday, Jupiter and Saturn will appear so close that a pinkie finger at arm’s length will easily cover both planets.
The planets haven't passed this closely in 400 years, and it's been nearly 800 years since this "Great Conjunction" has occurred at night, NASA says.
"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."
HOW TO SEE IT
In San Diego County, viewers can see the planets without needing a telescope by looking toward the southwest horizon just after sunset, NASA says, but a pair of binoculars or a small telescope will only enhance the view.
The best way to see the phenomenon is by finding an unobstructed view of the sky from say a park or field. The sight should even be viewable from most cities, but the site will only be visible after sunset for about one to two hours.
To tell the two planets apart prior to Monday when they switch positions in the sky, Jupiter will look like a bright star and be easily seen, while Saturn will look slightly fainter and slightly above and to the left of Jupiter.
For photographers, NASA recommends using a long exposure time to take in enough light as it gets dark. Both cell phone camera and DSLR camera users are encouraged to use a tripod to reduce any shaking during a long exposure.
Cell phone users may even want to use "night mode" or a wide-angle lens if available. DSLR users may consider setting their focus to manual and leaving their aperture wide open to let in as much light as possible.
Jupiter and Saturn should be bright enough to allow photographers to capture the planets without needing to zoom, NASA says. More of NASA's photography tips can be found online here.