The Rhythm of the Spheres

Reading the Night Sky

Wandering in Astronomy

The night sky is the oldest pattern of man, and every culture reads it differently. The stars above keep silent time, moving to a rhythm we are just now beginning to understand. Astronomy is where math, science, art, music, and words meet in a wondrous collision. In this section of our site, learn the basics of astronomy: from how a star chart is made, to projections and art that map the night sky, to how an astrolabe works just like it did thousands of years ago. Watch the North Star shift across centuries, explore how one sky has been mapped by many traditions, read what happened on this day in space, and see tonight’s moon for your location.

Map the Stars

The math behind star charts, with a projection explorer and a working astrolabe.

The Moving Sky

How the sky shifts across centuries, with a precession clock you can run.

The Traditions

One sky reads many ways, with a same-sky overlay of the world’s constellations.

This Day in the Stars

The sky’s events, discoveries, and lore tied to today’s date.

The Moon Tonight

Its phase and face, drawn live for where you’re standing.

✦  Astronomy Picture of the Day  ✦

NGC 2170: Still Life with Reflecting Dust

July 7, 2013
© Adam Block
In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines at the upper left. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a compact red emission region, and streamers of obscuring dust against a backdrop of stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured here are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation of the Unicorn (Monoceros). The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be about 15 light-years across. Follow APOD on: Facebook (Daily) (Sky) (Spanish) or Google Plus (Daily) (River)

Customized Star Charts Coming 1st Quarter 2027

We respect your privacy. Unsubscribe at any time.

✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
Astronomy Sep 7, 2026

The DESI legacy imaging survey releases the largest 2D map of the universe

In 2012, the Dark Energy Spectroscopic Instrument (DESI) was commissioned to measure the effect of dark energy, the mysterious force driving the expansion of the cosmos. Since then, the DESI Legacy…

Read
Astronomy Sep 7, 2026

Pair of white dwarfs locked in 6-minute orbit might one day be observed by gravitational waves

Current gravitational-wave observatories aren't sensitive enough to capture the gravitational waves of binary stars. They can only see the gravitational chirps of black holes just as they are mergi…

Read
Astronomy Sep 7, 2026

Rare pulsar unleashes 114 giant pulses in a single hour

Astronomers have detected extreme, never-before-seen behavior from a rare kind of pulsar and stumbled on a surprising link to one of astronomy's biggest current mysteries. Using 174 hours of radio …

Read
Human Spaceflight Sep 7, 2026

Sept. 7, 1914: The birth of James Van Allen

James Van Allen, who was born in Iowa on Sept. 7, 1914, showed talent and interest in science and math from an early age. A major in physics from Wesleyan College in 1935 was followed by a Ph.D. in…

Read
Exoplanets Sep 7, 2026

Why aren’t free-floating planets captured when they fly past stars?

Wouldn’t a free-floating planet eventually cross paths with a star or even a black hole and start revolving around it? YinToronto, Ontario Free-floating planets (FFPs) or rogue planets are bodies…

Read
Earth Sep 7, 2026

Reef fish survival threatened by motorboat noise

Reef fish exposed to motorboat noise can end up smaller and struggle to escape predators, says new research into dangerous underwater noise.

Read
Sun Sep 7, 2026

Sun news: Sun-stuff bursts could trigger strong auroras

Sun news September 7, 2026: A convoy of CMEs is racing our way. G1-G2 storms are likely, with G3 possible. Auroras may reach New York and London!

Read
Observing Sep 7, 2026

The Sky Today on Monday, September 7: Venus and Spica, side by side

Looking for a sky event this week? Check out our full Sky This Week column.  September 6: The Moon and Mars in Gemini Venus has pulled away from the bright star Spica in Virgo, which…

Read
Astronomy Essentials Sep 7, 2026

Visible planets and night sky guide for September

Visible planets and night sky guide: Tomorrow before sunrise, look for bright Jupiter near the thin crescent moon. This is a can’t-miss celestial event!

Read