Messier 3

Messier 3 holds more than 500,000 stars.

Distance

34,000 light-years

Apparent Magnitude

6.2

constellation

Canes Venatici

object type

Globular Cluster

Hubble view of M3
This image of M3’s core was constructed using Hubble observations in visible and infrared light.
NASA, ESA, STScI and A. Sarajedini (University of Florida)

The globular cluster M3 was the first object in the Messier catalog to be discovered by Charles Messier himself. Messier spotted the cluster in 1764, mistaking it for a nebula without any stars. This misunderstanding of M3’s nature was corrected in 1784 when William Herschel was able to resolve the cluster’s individual stars. Today it is known to contain over 500,000 stars.

M3 is notable for containing more variable stars than any other known cluster. The brightness of a variable star fluctuates with time. For some variable stars, their period relates to their intrinsic luminosity, so astronomers can use those stars’ brightness fluctuations to estimate their distances. This makes them extremely useful for measuring distances to deep-sky objects. M3 contains at least 274 variable stars.

The cluster is located 34,000 light-years from Earth in the constellation Canes Venatici. It has an apparent magnitude of 6.2 and can be spotted using a pair of binoculars. The best time to observe M3 is during June.

For more information about Hubble's observations of M3, see:

Annotated star chart of Messier 3 for the northern hemisphere.
This star chart for M3 represents the view from mid-northern latitudes for the given month and time.
Image courtesy of Stellarium
Annotated star chart of Messier 3 for the southern hemisphere.
This star chart for M3 represents the view from mid-southern latitudes for the given month and time.
Image courtesy of Stellarium

Explore Hubble's Messier Catalog

The following pages contain some of Hubble’s best images of Messier objects.

Bright green, orange, and yellow tendrils intertwined within this egg shaped nebula.

Messier 1 (The Crab Nebula)

Better known as the Crab Nebula, Charles Messier originally mistook Messier 1 for Halley’s Comet, which inspired him to create…

A Hubble image of a ball of thousands of stars

Messier 2

Hubble's image of Messier 2 is comprised of visible and infrared wavelengths of light.

More Things Hubble

  • nearly spherical gathering of white stars at center top. Blue gas cloud extends from top left to center bottom

    Hubble Science Highlights

    Hubble’s most notable scientific discoveries reflect the broad range of research and the breakthroughs it has achieved.

  • Upper left: "Hubble Focus" opening of the telescope is the "O" Center: bright-white star, Center Bottom: Orange-red planet with cloud bands, Center: small, bright-white star and very small red-orange dwarf star

    Hubble E-books

    Investigate the mysteries of the universe with Hubble. Learn Hubble's history. E-books dive deeper into Hubble discoveries and more.

  • An astronaut stands in front of a background of a nebula against a deep field of galaxies. The words "Name That Nebula" hovers above.

    Hubble Online Activities

    Find your Hubble birthday image, take interactive tours, play games, and more.

  • c39-2b

    Caldwell Catalog

    Your backyard telescope and binoculars may not have the capabilities of Hubble, but you can still see amazing objects. Compare what you see with the images Hubble has taken.