
Update: 7:49 p.m. The Lick Observatory is saying a meteor caused the light. Writing on Facebook, the University of California-owned observatory, said a “bright meteor was visible in the skies over the Bay Area shortly after sunset this evening, leaving a bright trail that was visible for many minutes in the western sky. “
Original story: A mysterious light in the sky that popped up over the Bay Area around 5:30 p.m. has people wondering whether it is the trail from a rocket launch, a meteor entering the earth’s atmosphere, space debris, a strange cloud formation, or the reentry of a Russian rocket. Some even jokingly said it was Santa on his sleigh.
Berkeleyside has reached out to NASA for information, but so far no one is responding to inquiries.
One thing it is not is a Delta IV rocket that was scheduled to launch from Vandenberg Air Force Base at 5:44 p.m. The launch was delayed because of a hydrogen leak, according to the San Luis Obispo Tribune.
The Russian Soyuz spacecraft was too far away to account for the light. It was scheduled to undock from the International Space Station at 5:42 p.m. and take three and a half hours to reach the earth’s atmosphere, according to Nasa.
Video below by David Jacobowitz:

The light was both beautiful and mysterious, hovering horizontally across the sky. It looked as if the sun were peeping through clouds, although the sun had already set. The light was seen as far northwest as Reno, Nevada and as far south as Vandenberg.
People had many reactions to the light. Many thought the light was caused by a meteor. When one explodes in the earth’s atmosphere it is called a bolide. But no official has confirmed that.
The National Weather Service in Hanford has suggested it is a noctilucent cloud, which, according to Wikipedia, “are tenuous cloud-like phenomena in the upper atmosphere of Earth. They consist of ice crystals and are only visible during astronomical twilight.”
Here is a NASA video about them.
Here is an excellent video of the light:

The Delta IV rocket launch was scrubbed this evening at Vandenberg AFB. Did anyone else see this beautiful sunset and light in the western sky? This is a view from the Diamond Peak @NVSeismoLab AlertTahoe camera. pic.twitter.com/2ekBnRfFRq
— NWS Reno (@NWSReno) December 20, 2018
https://twitter.com/Richifornia/status/1075569646030381056
From this video shot from Stockton, the strange cloud is definitely the smoke trail of a meteor. @berkeleyside @KTVU @NWSBayArea https://t.co/8Qfoj8NC4i
— Boosted, mask wearing Yoda (@seanyodarouse) December 20, 2018
Anyone know what caused this irregular contrail (at 5:37 pm)?@berkeleyside pic.twitter.com/B0XSN5U0sb
— Lisa Fine (@Lisa_Fine) December 20, 2018
Here's my shot. pic.twitter.com/enPxzRThKa
— Jenifer MacGillvary (@JMacGillvary) December 20, 2018
Here’s another shot @berkeleyside pic.twitter.com/KFfbM0PtgB
— 🏳️🌈 Lori Droste (@loridroste) December 20, 2018
One person is trying to crowdsource the light’s origin. He is asking people to “triangulate” its origins by filling in this survey about where it was spotted.
Berkeleyside updated this story as we got more information.