The Abridged version:
- Sacramento’s last supermoon of the year is Thursday.
- Watching the moon rise at 4:19 p.m. can make it appear enormous as it crosses the horizon.
- Clear, crisp air and early sunsets make Northern California one of the best places for sky watchers.
Sacramentans are in the perfect spot to look skyward late Thursday afternoon and throughout the evening as the year’s final supermoon climbs above the Sacramento Valley. A bright, crisp orb will emerge above the horizon at 4:19 p.m. and rise over the skyline within minutes. The supermoon will be visible until 8:19 a.m. Friday.
Weather-wise, it looks like the supermoon will arrive at an ideal time. Days of tule fog should finally thin — unveiling an unobstructed sky that will make the moon appear startlingly close.
A supermoon happens when a full moon aligns with the moon’s closest point to Earth in its orbit, known as perigee. The result is a moon that appears slightly larger and about 30 percent brighter. Thursday’s full moon will be the third — and final — supermoon of 2025.
What makes a supermoon?
Astronomy lecturer Laura Legé with Sacramento State’s planetarium explained what a supermoon is — and why this one is such a treat for Northern California.
She said a supermoon occurs when the moon’s closest point to Earth lines up with the full moon phase.
“So how they usually classify supermoons is a full moon that happens when it is within 90 percent of its closest distance to us,” she said. That closest distance, perigee, will happen early Thursday morning at 3 a.m. The moon becomes officially full Thursday at 4:19 p.m.
Legé says watching the moon rise near the horizon can make it feel enormous.
“It will look very big to you, but that is mostly because of the moon illusion,” she said. “Your eyes and brain play a little trick on you.”
But she said you can break that trick in a way that’s simple, and almost playful. “If you hold out your little finger at arm’s length and measure the moon when it is high and when it is low, you can actually break the moon illusion yourself,” she said.
Visibility for this week’s supermoon is expected to be strong from the moment it rises through Thursday night. Legé notes that conditions should become great for moon watching as early as Wednesday, with cloud cover thinning mid-week and the moon visibly bright.
Sacramento region is ripe for winter sky watchers
Legé says Northern California is one of the best places for winter sky watching.
“Winter clear nights are the best nights to go out,” Legé said. “You do not have to stay up late, and the air is clear and crisp. We usually do not have a lot of turbulent air over us that time of year.”
The chilly winter air makes night sky viewing unusually sharp and steady. Sacramento is one of the top places in Northern California where winter sky conditions can be ideal when the weather cooperates. That’s one of the reasons Legé gives monthly presentations at the Sacramento State Planetarium.
“I absolutely love it when anyone at anytime is interested in what’s going on in the night sky. It’s my bread and butter. It’s how I got into astronomy,” she said.
And a bit of humor in closing, while professing a deep love of watching the moon, Legé quipped: “Hmm, you’re a lunatic.”
Rob Stewart is an executive producer and reporter with Abridged.