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.

โœฆ  Astronomy Picture of the Day  โœฆ

The Largest Satellites of Earth

June 12, 2023
Credit: Tianyao Yang
See this entry on NASA's APOD โ†’
What's that near the Moon? It's the International Space Station (ISS). Although the ISS may appear to be physically near the Moon , it is not โ€” it is physically near the Earth . In low Earth orbit and circulating around our big blue marble about every 90 minutes, the ISS was captured photographically as it crossed nearly in front of the Moon . The Moon, itself in a month-long orbit around the Earth, shows a crescent phase as only a curving sliver of its Sun-illuminated half is visible from the Earth. The featured image was taken in late March from Shanghai , China and shows not only details of Earth's largest human-made satellite, but details of the cratered and barren surface of Earth's largest natural satellite. Over the next few years, humanity is planning to send more people and machines to the Moon than ever before.

Customized Star Charts Coming 1st Quarter 2027

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โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
Astronomy Nov 9, 2026

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