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  ✦

M106 Close Up

May 3, 2012
Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe: a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with prominent dust lanes and a bright central core, this colorful composite image highlights youthful blue star clusters and reddish stellar nurseries that trace the galaxy's spiral arms. The high resolution galaxy portrait is a mosaic of data from Hubble's sharp ACS camera combined with groundbased color image data. M106 (aka NGC 4258) is a nearby example of the Seyfert class of active galaxies, seen across the spectrum from radio to X-rays. Energetic active galaxies are powered by matter falling into a massive central black hole.

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✦  EarthSky  ·  Astronomy.com  ·  Phys.org  ✦
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