Space
Arecibo data lives on, provides new galaxy insights
Despite the collapse of the Arecibo radio telescope in 2020, astronomers are still using Arecibo data to make new insights into our universe.
Tonight
Moon, Jupiter, Saturn, Venus December 6 to December 9
Wow! What a sight. The moon, Jupiter, Saturn, Venus all in your western sky after sunset. Watch for them December 6 to 9, 2021.
Tonight

Earliest sunset for 40 degrees north around now

Earliest sunset at mid-northern latitudes are happening now. What if you're in the Southern Hemisphere? Watch for your earliest sunrise.
Space

Hera mission following after DART’s asteroid impact

The Hera mission will take over after DART impacts an asteroid. Hera will analyze the impact area and learn more about Didymos and Dimorphos.
Space

False fossils on Mars might inhibit search for life

A new study from scientists in the UK says that false fossils on Mars could complicate the search for microbial life. They could be mistaken for real fossils.
Today's Image

Photos and video: December 4 total solar eclipse

Photos and video, December 4, 2021, total solar eclipse. It was visible along a narrow path - the path of totality - that crossed Antarctica.
Astronomy Essentials

Comet Leonard, and its glorious sweep past M3

The first comet to be found in 2021 was Comet Leonard (C/2021 A1). It might become the brightest comet of this year! Charts and more info here.
Earth

Tides, and the pull of the moon and sun

Expect higher-than-usual tides a day or two after the December 3-4, 2021, total eclipse of the sun. The moon will be both new and closest to Earth.
Constellations

Horologium the Pendulum Clock, best in December

Horologium the Pendulum Clock is a constellation that lies in southern skies. Observers can best spot this constellation around the month of December.
Astronomy Essentials
Sun

Total solar eclipse of December 4, 2021

A total solar eclipse occurs December 4, 2021. The total phase sweeps over Antarctica, while the partial phase reaches southernmost points of three continents.