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

Visualization: A Black Hole Accretion Disk

May 8, 2024
Credit: Visualization Credit: NASA 's Goddard Space Flight Center , Jeremy Schnittman
See this entry on NASA's APOD โ†’
What would it look like to circle a black hole? If the black hole was surrounded by a swirling disk of glowing and accreting gas , then the great gravity of the black hole would deflect light emitted by the disk to make it look very unusual. The featured animated video gives a visualization. The video starts with you, the observer , looking toward the black hole from just above the plane of the accretion disk. Surrounding the central black hole is a thin circular image of the orbiting disk that marks the position of the photon sphere -- inside of which lies the black hole's event horizon . Toward the left, parts of the large main image of the disk appear brighter as they move toward you. As the video continues, you loop over the black hole , soon looking down from the top, then passing through the disk plane on the far side, then returning to your original vantage point . The accretion disk does some interesting image inversions -- but never appears flat. Visualizations such as this are particularly relevant today as black holes are being imaged in unprecedented detail by the Event Horizon Telescope .

Singularity Impressive: It's Black Hole Week at NASA!

Customized Star Charts Coming 1st Quarter 2027

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โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
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