![Request for Information – Potential [Placeholder for Prize]](https://assets.science.nasa.gov/dynamicimage/assets/science/psd/solar/2023/09/s/solarsystem_0.jpg?w=1024)
APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
M4: The Closest Known Globular Cluster
Explanation: M4 is a globular cluster visible in dark skies about one degree west of the bright star Antares in the constellation Scorpius . M4 is perhaps the closest globular cluster at 7000 light years , meaning that we see M4 only as it was 7000 years ago, near the dawn of recorded human history . Although containing hundreds of thousands of stars and spanning over 50 light-years, M4 is one of the smallest and sparsest globular clusters known. A particularly unusual aspect for a globular cluster is M4 's central bar of stars. M4, pictured above , is one of the oldest objects for which astronomers can estimate age directly. Cluster white dwarfs appear to be at least nine billion years old - so ancient they limit the youth of our entire universe .
| Date | May 23, 2000 |
|---|---|
| Credit | Credit & Copyright: T2KA , KPNO 0.9-m Telescope , NOAO , AURA , NSF |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |