Key Information
Hoag’s Object
| Type | Ring Galaxy |
| Diameter | 148,000 light years |
| Distance | 594.3 million light years |
| Total Stars | 100 to 500 billion stars |
| Date of Discovery | 1950 |
Learning Point
- Hoag’s Object is one of the universe’s most rare and mysterious sights: a ring galaxy that looks like a perfect celestial bullseye. This unique structure features a core of old, yellow stars separated by a vast, empty gap from a massive, perfectly circular outer ring of young, bright blue stars. Located 600 million light-years away, its perfectly symmetrical appearance puzzles scientists because the usual explanation for ring galaxies—a head-on collision with another galaxy—does not seem to fit.
Project
- Identify other objects similar to Hoag’s Object and assess how they are similar or different.
- Overview
- Real Photo
Location
| Location | Serpens Caput constellation |
Fun Facts
- The stars in the galaxy are separated by color and age! The small, round center is made of old, yellowish stars, but the huge outer ring is made of very young, hot, and bright blue stars.
- Scientists don’t know exactly how it formed! They think most “ring galaxies” are made when one galaxy crashes right through the center of another, but there’s no sign of a “crashed” galaxy near Hoag’s Object.
- If you look very closely at pictures from the Hubble Space Telescope, you can see another, much smaller ring galaxy sitting inside the dark gap of Hoag’s own ring!
- You would need to travel for about 600 million years at the speed of light to reach Hoag’s Object, which means when you look at it, you are seeing it as it was 600 million years ago!
Past Lessons
| 149 | October 7, 2025 | (North America) |