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

Dragon's Egg Bipolar Emission Nebula

April 24, 2024
Credit: Rowan Prangley
See this entry on NASA's APOD โ†’
How did a star form this beautiful nebula? In the middle of emission nebula NGC 6164 is an unusually massive star . The central star has been compared to an oyster's pearl and an egg protected by the mythical sky dragons of Ara . The star, visible in the center of the featured image and catalogued as HD 148937 , is so hot that the ultraviolet light it emits heats up gas that surrounds it. That gas was likely thrown off from the star previously, possibly the result of a gravitational interaction with a looping stellar companion. Expelled material might have been channeled by the magnetic field of the massive star, in all creating the symmetric shape of the bipolar nebula . NGC 6164 spans about four light years and is located about 3,600 light years away toward the southern constellation Norma .

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โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
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