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  ✦

In the Shadow of Saturn's Rings

July 3, 2012
Humanity's robot orbiting Saturn has recorded yet another amazing view. That robot, of course, is the spacecraft Cassini, while the new amazing view includes a bright moon, thin rings, oddly broken clouds, and warped shadows. Titan, Saturn's largest moon, appears above as a featureless tan as it is continually shrouded in thick clouds. The rings of Saturn are seen as a thin line because they are so flat and imaged nearly edge on. Details of Saturn's rings are therefore best visible in the dark ring shadows seen across the giant planet's cloud tops. Since the ring particles orbit in the same plane as Titan, they appear to skewer the foreground moon. In the upper hemisphere of Saturn, the clouds show many details, including dips in long bright bands indicating disturbances in a high altitude jet stream. Recent precise measurements of how much Titan flexes as it orbits Saturn hint that vast oceans of water might exist deep underground. APOD in Spanish: On the web and through Facebook

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
Today in the History of Astronomy Sep 19, 2026

Sept. 19, 1959: A SETI kickstart

On Sept. 19, 1959, the paper “Searching for Interstellar Communications” was published. Printed in the respected scientific journal Nature and written by Cornell University physicists Giuseppe …

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Scientists discover a new tiger cat hiding in plain sight

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Astronomy Essentials Sep 19, 2026

International Observe the Moon Night 2026 is tonight

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Astronomy Essentials Sep 19, 2026

Visible planets and night sky guide for September

Visible planets and night sky guide: Tonight is International Observe the Moon Night. And see a video about upcoming sky events.

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Observing Sep 19, 2026

The Sky Today on Saturday, September 19: Mars meets Pollux

Looking for a sky event this week? Check out our full Sky This Week column.  September 18: The Lizard’s brightest cluster Mars passed 6° due south of Pollux in Gemini at midnight …

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Astronomy Sep 18, 2026

Hubble spots an out-of-sync galaxy

Though the spiral galaxy in this new image from the NASA/ESA Hubble Space Telescope seems serene, it hides a chaotic secret. This galaxy is NGC 4698, and it lies about 55 million light-years away i…

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Astronomy Sep 18, 2026

From the start, the solar system chose fire over ice to build its first bodies

When the solar system first took up the task of building solid bodies—such as planets, moons and protoplanets—it basically had a choice between two ingredients: heat-forged chondrules, which we…

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Astronomy Sep 18, 2026

Time is running out to catch a giant planet's strange orbit

A team of researchers, including those from the University of Tokyo, spotted a rare kind of planet that's unusually hot and eccentric. TOI-1355 b orbits its star, TOI-1355, which is also much hotte…

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Science Sep 18, 2026

Still going strong: Hubble’s 36th anniversary image

Life in space is hard. Most orbiting observatories retire well before their 20th birthday. Yet the Hubble Space Telescope has survived and continues to thrive well into its 30s. Astronomers celebra…

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