Welcome to StarDate

Home of America’s longest-running national daily astronomy radio feature.
And so much more.

Stardate:

September 20, 2026

Radio: Today’s Episode

Errai
September 20, 2026
A future inconstant North Star

Premium Same-Day Audio Access lets you stream episodes of StarDate the same day they air.
Log in or subscribe now to listen!

Radio: Yesterday’s Episode

Circumpolar Stars
September 19, 2026
Stars that never set

StarDate
Circumpolar Stars

00:00 / 00:02:20

Apple Podcasts Pandora Spotify
RSS Feed

Share

Link

Embed

Download file | Play in new window
Subscribe: Apple Podcasts | Pandora | Spotify

Stargazing

September 20, 2026
Errai
Polaris stands almost due north, so all the other stars in the northern hemisphere appear to wheel around it as Earth turns on its axis. But Polaris will slide away from that spot. About 1,200 years from now, it will be replaced by Errai, in Cepheus the king.
September 19, 2026
Circumpolar Stars
The Big Dipper is low in the northwest at nightfall, and in the northeast at first light tomorrow. W-shaped Cassiopeia is just the opposite – in the northeast at nightfall, and the northwest at dawn.
September 18, 2026
First-Quarter Moon
The Moon is at first quarter today. Sunlight illuminates exactly one-half of the lunar hemisphere that faces Earth. The sunlit portion of the Moon will increase until the Moon is full on September 25 – the Harvest Moon.

Launch Stargazing Tips

Moon Phases

At the new Moon phase, the Moon is so close to the Sun in the sky that none of the side facing Earth is illuminated (position 1 in illustration). In other words, the Moon is between Earth and Sun. At first quarter, the half-lit Moon is highest in the sky at sunset, then sets about six hours later (3). At full Moon, the Moon is behind Earth in space with respect to the Sun. As the Sun sets, the Moon rises with the side that faces Earth fully exposed to sunlight (5).

Launch Current Moon Phase

Today’s Sponsor

Support StarDate by sponsoring for a day!

Stardate Magazine

Current Issue: SEPTEMBER/OCTOBER 2026

Galactic Excavations

by Kristen Pope

Space telescopes and other tools are helping astronomers become archaeologists, allowing them to dig into the histories of other galaxies, and we’ll cover some of their discoveries. We’ll also preview the launches of two major space missions: the next big space telescope and an expedition to investigate the moons of Mars.