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  ✦

Comet Lemmon and the Deep Sky

July 20, 2013
© Nick Martin
Now sweeping high above the ecliptic plane, Comet Lemmon has faded dramatically in planet Earth's night sky as it heads for the outer solar system. Some 16 light-minutes (2 AU) from the Sun, it still sports a greenish coma though, posing on the right in this 4 degree wide telescopic view from last Saturday with deep sky star clusters and nebulae in Cassiopeia. In fact, the rich background skyscape is typical within the boundaries of the boastful northern constellation that lie along the crowded starfields of the Milky Way. Included near center is open star cluster M52 about 5,000 light-years away. Around 11,000 light-years distant, the red glowing nebula NGC 7635 below and left of M52 is well-known for its appearance in close-up images as the Bubble Nebula. But the fading Comet Lemmon is not the only foreground object on the scene. A faint streak on the right is an orbiting satellite caught crossing through the field during the long exposure, glinting in the sunlight and winking out as it passes into Earth's shadow. Interplanetary News: Photo Op from Cassini and MESSENGER - just be sure to smile and wave.

Customized Star Charts Coming 1st Quarter 2027

We respect your privacy. Unsubscribe at any time.

✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
Sun Sep 9, 2026

Sun news: Sun-blasts arrive with strike two

Sun news September 9, 2026: Strike two! A second CME sparked another G1 storm at 17:44 UTC. More are arriving today, so G2 storms and auroras are possible.

Read
Observing Sep 9, 2026

The Sky Today on Wednesday, September 9: Visualize the ecliptic

Looking for a sky event this week? Check out our full Sky This Week column.  September 8: The Moon joins Jupiter The waning Moon has moved from Cancer to Leo and is nearing the brigh…

Read
Tonight Sep 9, 2026

Orion’s Belt points to Sirius on September mornings

Use Orion's Belt to find Sirius, the sky's brightest star. In 2026, Jupiter is in the same region, outshining even Sirius.

Read
Astronomy Sep 9, 2026

Some black holes grow much faster than their galaxies

Nearly every galaxy has a supermassive black hole. The few that don't have had theirs ejected during a galactic collision. That's because galaxies and their black holes have formed hand in hand. Th…

Read
What's Launching This Week Sep 8, 2026

SpaceX closes out SES’s O3b mPower constellation

Rocket launches this week On Thursday, Sept. 10 at 5:00 a.m. EST, a Long March 2D rocket is set to lift off from Jiuquan Satellite Launch Center in northern China’s Gobi Desert carrying an undisc…

Read
Astronomy Sep 8, 2026

Extremely massive galaxy proto-supercluster smashes distance record

An international team of astronomers has discovered the most distant progenitor to a galaxy supercluster ever. The discovery supports existing theories of how galaxy clusters evolve and reveals how…

Read
Astronomy Sep 8, 2026

Fast radio bursts could help disentangle galactic feedback from dark matter effects

Intense, brief flashes of radio light called fast radio bursts (FRBs) travel across billions of light-years to reach Earth, passing through a fog of matter along the way. The bursts' origins are un…

Read
Robotic Spaceflight Sep 8, 2026

Sept. 8, 2016: OSIRIS-REx launches

On Sept. 8, 2016, the Origins, Spectral Interpretation, Resource Identification, and Security – Regolith Explorer (OSIRIS-REx) mission launched from Cape Canaveral, setting off on its 4.4-billion…

Read
Astronomy Essentials Sep 8, 2026

How many stars can you see on a moonless night?

Have you ever wondered how many stars are visible on a given night? It depends on factors including how dark your sky is and what your age is.

Read