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  ✦

Earth at Night

December 7, 2012
This remarkably complete view of Earth at night is a composite of cloud-free, nighttime images. The images were collected during April and October 2012 by the Suomi-NPP satellite from polar orbit about 824 kilometers (512 miles) above the surface using its Visible Infrared Imaging Radiometer Suite (VIIRS). VIIRS offers greatly improved resolution and sensitivity compared to past global nightlight detecting instrumentation on DMSP satellites. It also has advantages compared to cameras on the International Space Station. While the space station passes over the same point on Earth every two or three days, Suomi-NPP passes over the same point twice a day at about 1:30am and 1:30pm local time. Easy to recognize here, city lights identify major population centers, tracking the effects of human activity and influence across the globe. That makes nighttime images of our fair planet among the most interesting and important views from space.

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
Observing Aug 31, 2026

2026 Full Moon calendar: When to see the Full Moon and phases

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Astronomy Aug 31, 2026

Four 'Little Red Dot' pairs hint at black hole mergers in early universe

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What's Launching This Week Aug 31, 2026

Norway, India, and New Zealand target launches as Starlink continues

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Space Aug 31, 2026

How do lava-world exoplanets keep their atmospheres?

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Astronomy Aug 31, 2026

Manganese's emission lines shine a light on galactic evolution

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Astronomy Aug 31, 2026

Solar orbiter detects ion sorting at the solar wind's magnetic boundary

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Human Spaceflight Aug 31, 2026

Why do astronauts get constipated?

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Earth Aug 31, 2026

Giant trees break a decades-old science theory

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Earth Aug 31, 2026

Lake Powell hits record low, continues to drop

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