The big moment is here.

Not only is today the first day of winter, but tonight, a celestial event 800 years in the making will shine over Long Beach and the rest of the world.

Jupiter and Saturn will align to form what’s known as the “Great Conjunction.” The two planets will be so close in the night sky that they almost appear as a single shining object.

Also referred to as the ‘Christmas Star,’ the phenomenon will appear in the southwest sky not long after sunset.

The National Aeronautics and Space Administration released tips for viewing a once-in-a-lifetime sight Monday night.

“This will still be quite a striking sight, but you will need to look fast as both planets will set shortly after sunset,” NASA’s website says.

Here are some viewing tips from NASA:

  • Monday night, find a spot with an unobstructed view of the southern sky, such as Bluff Park, the Long Beach Shoreline, or Hilltop Park at the top of Signal Hill (sorry about the traffic, Signal Hillians. Hillers? Highlanders?).
  • Look into the southwestern sky about an hour after sunset, which for Long Beach, is 4:49 p.m. tonight.
  • Cross your fingers that the Palos Verdes Peninsula isn’t blocking the view like an annoying younger sibling standing in front of the TV during Saturday morning cartoons. Sit down, Rolling Hills!
  • If you looked before Monday, you could have seen that Saturn will be slightly fainter and appear just above and to the left of Jupiter. During the “Great Conjunction,” Jupiter overtakes Saturn and the two reverse positions in the sky.

Tonight’s event will be the closest Jupiter and Saturn have appeared since March 4, 1226.

Obviously, Jupiter and Saturn aren’t truly close together—Jupiter is approximately 551 million miles from Earth, or over five times the distance as Earth is from the Sun, while Saturn sits nearly twice as far away as Jupiter, at one billion miles from Earth.

If you can’t make it outdoors, locally, the Mount Wilson Observatory will be hosting a virtual star party on YouTube tonight starting at 5 p.m.