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

Hoag's Object: A Nearly Perfect Ring Galaxy

February 18, 2024
Credit: NASA , ESA , Hubble ; Processing: Benoit Blanco
See this entry on NASA's APOD โ†’
Is this one galaxy or two? This question came to light in 1950 when astronomer Arthur Hoag chanced upon this unusual extragalactic object. On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older. Between the two is a gap that appears almost completely dark. How Hoag's Object formed, including its nearly perfectly round ring of stars and gas, remains unknown. Genesis hypotheses include a galaxy collision billions of years ago and the gravitational effect of a central bar that has since vanished . The featured photo was taken by the Hubble Space Telescope and reprocessed using an artificially intelligent de-noising algorithm . Observations in radio waves indicate that Hoag's Object has not accreted a smaller galaxy in the past billion years. Hoag's Object spans about 100,000 light years and lies about 600 million light years away toward the constellation of the Snake ( Serpens ). Many galaxies far in the distance are visible toward the right, while coincidentally , visible in the gap at about seven o'clock, is another but more distant ring galaxy .

Customized Star Charts Coming 1st Quarter 2027

We respect your privacy. Unsubscribe at any time.

โœฆ  EarthSky  ยท  Astronomy.com  ยท  Phys.org  โœฆ
Astronomy Nov 6, 2026

Astronomers deliver the sharpest and deepest view yet of the low-frequency radio sky

Using the Low Frequency Array (LOFAR), an international team led by Leiden University has produced the sharpest and most sensitive radio image of the sky ever made at low radio frequencies. The imaโ€ฆ

Read
Astronomy Nov 5, 2026

Connecting artificial intelligence with the tools of astrophysical research

Investigating a scientific question is often a complex process. As an astrophysicist studying some of the most energetic phenomena in the universe, I know that finding answers requires much more thโ€ฆ

Read
Astronomy Nov 5, 2026

Hubble learns galactic history from stars

This NASA/ESA Hubble Space Telescope image provides a lesson in galactic history. The sparkling collection of stars is named Messier 30 (M30) after the French astronomer Charles Messier, who cataloโ€ฆ

Read
Telescopes and Equipment Nov 5, 2026

Make the most of long nights with this monthโ€™s new astronomy products

GS-100AR/AC High-Precision Guide Scope ToupTekHangzhou, China The GS-100AR/AC High-Precision Guide Scope is a guide scope, a wide-field imaging system, and a visual instrument. Its apochromatic desโ€ฆ

Read
Space Nov 5, 2026

Hera mission gets its 1st closeup view of Didymos and Dimorphos

The Hera mission just got its 1st closeup view of Didymos and its little moonlet Dimorphos. Soon it will begin investigating the aftermath of the DART impact.

Read
Solar System Nov 5, 2026

Curiosity captures a martian dawn

The morning Sun casts a hazy glow over Marsโ€™ Mount Sharp, lighting up distant wind-carved rock formations known as yardangs. This scene is cropped from a six-image panorama captured by the Mastcaโ€ฆ

Read
Robotic Spaceflight Nov 5, 2026

Nov. 5, 2006: Mars Global Surveyor goes quiet

Designed to study Mars in a comprehensive way, examining its atmosphere, its interior, and its surface, the Mars Global Surveyor (MGS) launched Nov. 7, 1996. By Sept. 12, 1997, it would reach Mars โ€ฆ

Read
Space Nov 5, 2026

Swift spacecraft fell back to Earth in a fiery blaze yesterday

The Swift spacecraft fell back to Earth as a fiery streak of light yesterday. See videos here of the blazing reentry into Earth's atmosphere.

Read
Space Nov 5, 2026

ESCAPADE mission to fly past Earth twice in 2 days

On November 7 and 9, 2026, the twin probes of the ESCAPADE mission โ€” first Blue and then Gold โ€” will perform flybys of Earth on the way to Mars.

Read