One of the brightest stars in the summer night sky will be occulted (eclipsed) by the moon this weekend in one of 2024’s rarest sky events for the Americas.

The 16th brightest star in the night sky, the brightest in the constellation Virgo and about 250 light-years distant, Spica is one of only four stars that can occulted (blocked) by the moon. That’s exactly what’s about to happen for sky-watchers in North America and Central America.

Here’s everything you need to know about this rare sky event, one of the stargazing highlights of 2024.

What Is The Occultation Of Spica?

It’s when Spica is covered by the moon for a few hours. It actually happens regularly, though, as well as often occurring in daylight, the geographical visibility is very limited. It just so happens that this occultation of Spica will be visible across North America and Central America—and nowhere else.

Habitual stargazers will know that the moon often appears very close to four stars in the night sky—Spica, Regulus in Leo, Antares in Scorpio and Aldebaran in Taurus. All get occulted from time to time.

As reported by In-The-Sky.org—which has an excellent map—a close conjunction of the moon and Spica will be visible across the world, but only North and Central America will see anything of the occultation.

When And Where Is The Occultation Of Spica?

Spica will be occulted by a First Quarter Moon (appearing half-lit as seen from Earth) between 21:40 EDT on Saturday, July 13 and 00:58 EDT on Sunday, July 14, according to In-The-Sky.org.

The process of occultation is perhaps a little surprising. Of course, all that’s happening is that the moon is moving in front of a star and blocking it for an hour or so. However, geography is everything.

There’s a narrow sweet spot where it will be possible to see Spica first disappear (ingress) behind the dark limb of the moon and then reappear (egress) from behind its brightly lit side. However, on either side will be grazing zones where viewers will only see one of those phases of the event. That’s the case on Saturday when North and Central America will be split into those three zones:

  • Disappearance only: Eastern U.S. states (11:30 p.m. EDT, low in the southwest).
  • Full occultation: Midwest U.S states(10:00 p.m. CDT)
  • Reappearance only: Northwestern U.S. states (9:00 p.m. MDT).

How To Find Spica On Any Summer Night

Have you ever gone “spike to Spica?” It’s one of the most famous “star hops” of all. Just find the Big Dipper, take the arc of its handle to the bright star Arcturus, and carry on to the only other bright star you can see—Spica. It’s particularly prominent in the summer night sky in the northern hemisphere.

Accorsing to The Planets, Spica comes from the Latin phrase spīca virginis, meaning “Virgo’s ear of grain,” and is actaully two stars that orbit each other every four days. They’re seven and three times the radius of the sun, much hotter, and are so close that they cannot be split in a telescope.

There will be another lunar occultation of Spica on Wednesday, November 27, but only for the eastern U.S. states.

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Wishing you clear skies and wide eyes.