Hubble’s Messier celestial snow globe


It’s beginning to look a lot like the holiday season in this NASA Hubble Space Telescope image of a blizzard of stars, which resembles a swirling snowstorm in a snow globe.

The stars are residents of the globular star cluster Messier 79, or M79, located 41,000 light-years from Earth, in the constellation Lepus. The cluster is also known as NGC 1904.

Globular clusters are gravitationally bound groupings of as many as 1 million stars. M79 contains about 150,000 stars packed into an area measuring only 118 light-years across. These giant “star-globes” contain some of the oldest stars in our galaxy, estimated to be 11.7 billion years old.

Most globular clusters are grouped around the central hub of our pinwheel-shaped galaxy. However, M79’s home is nearly on the opposite side of the sky from the direction of the galactic center. One idea for the cluster’s unusual location is that its neighborhood may contain a higher-than-average density of stars, which fueled its formation. Another possibility is that M79 may have formed in an unusual dwarf galaxy that is merging with the Milky Way.

In the Hubble image, Sun-like stars appear yellow. The reddish stars are bright giants that represent the final stages of a star’s life. Most of the blue stars sprinkled throughout the cluster are aging “helium-burning” stars. These bright blue stars have exhausted their hydrogen fuel and are now fusing helium in their cores.

The stars in the globular star cluster Messier 79 look a lot like a blizzard in a snow globe in this NASA Hubble Space Telescope image. CREDIT NASA and ESA, Acknowledgment: S. Djorgovski (Caltech) and F. Ferraro (University of Bologna)

A scattering of fainter blue stars are “blue stragglers.” These unusual stars glow in blue light, mimicking the appearance of hot, young stars. Blue stragglers form either by the merger of stars in a binary system or by the collision of two unrelated stars in M79’s crowded core.

The star cluster was discovered by Pierre Méchain in 1780. Méchain reported the finding to Charles Messier, who included it in his catalog of non-cometary objects. About four years later, using a larger telescope than Messier’s, William Herschel resolved the stars in M79, and described it as a “globular star cluster.”

The image is a combination of observations taken in 1995 and 1997 by Hubble’s Wide Field Planetary Camera 2. The red, green, and blue colors used to compose the image represent a natural view of the cluster.


The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

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For NASA’s Hubble website, visit:

For the Hubble Messier Catalog, visit:


27 thoughts on “Hubble’s Messier celestial snow globe

      • BINGO!
        I was thinking, “Hey this would be great to link up on my facebook page!” And then the “Happy Holiday” B.S. showed up at the end.

        “What’s do-day my fine fellow” said Scrooge.
        “Today?” Why it’s December 25!”
        “December 25th!” Said Scrooge to himself.
        “I haven’t missed it. Hallo, my fine fellow,
        Happy Holidays!”

  1. M79 contains about 150,000 stars packed into an area measuring only 118 light-years across.

    I make that to be around 13 stars per cubic light year. The nearest star to us (other than the sun) is around four light years away. That’s quite a difference in density.

    I’m guessing that in a dense star cluster things would be sufficiently chaotic that life would never have the time to evolve before being snuffed out by a collision or a gamma ray burst.

    • I had a similar thought, but you never know. The universe is not only stranger than we imagine, it’s stranger than we can imagine.

      • D. J. Hawkins
        December 13, 2017 at 6:54 am

        I had a similar thought, but you never know. The universe is not only stranger than we imagine, it’s stranger than we can imagine.
        Still, if I could have a saying, the Universe and the universe happens to be far far much simpler in principle than the astrophysics explanation stands for and the orthodoxy of the science tries to propagate……with all this complicated and “stranger than fiction” scenarios offered…

        But hey, who could contradict these severe egg shaped head ivory guys….they always know better…. !!!!


    • My calculator makes it about one star per eleven cubic light years.
      ‘150,000’ stars in 118 L/Years cubed..
      If globular [diameter = 118 L/Years, radius 59 L/years] – it’s about 5 or six cubic light years per star [860,000 roughly cubic light years for ‘150,000’ stars].

      Now, still, a considerable difference in density.


    • Trying to say Bah Humbug, by any chance?
      True enough, the CCD camera is intensity only, so you get a gray scale out. The Hubble camera is also equipped with a variety of both narrow band, and wide band optical filters to provide color information. The fabulous color images are not always false color, but are composites obtained with different filters.

    • Hubble has 48 filters to image a variety of wavelengths. The detectors measure light. But what light gets there is determined by what filter is being used.

      I am a former STSci employee.

  2. Seems that you calculated the area of a circle rather than the volume of a sphere. I find 0.17 stars per light year

    • Maybe, maybe not? The Goddard release says “area.” They count 150K visible stars in the visible field? There are 150K stars total?

      Never let a mathematically illiterate PR department get hold of your data…

      (Hint to writers – you can use “region” to be accurate without being pedantic.)

  3. If a civilization on a planet stable enough (not sure about such a thing in there) around a star in a cluster and evolved to a technological stage…. just imagine: they wouldn’t have a clue what the word ‘dark’ mean. Couldn’t see beyond the cluster …. from all the dazzling light from all those stars.
    On the other-hand it would make a great Sci-Fi novel of an old empire story in a cluster… the stars and planets are so close to each other, colonization (and wars) would be very easy. Would make a great SGI!

    • >>
      If a civilization on a planet stable enough . . . .

      I don’t mind Sci-Fi authors playing around with known physical laws and observations to build a good story/plot just as long as they try to keep the other science stuff accurate.

      You’ll find that globular clusters are very old objects that are composed of Population II stars (the Sun is a Population I star–and yes I have to look it up every time to be sure). Population II stars lack heavier elements above hydrogen and helium (and lithium and beryllium), so terrestrial planets like Earth would be unlikely.

      The movement of stars in a globular cluster are more like a swarm of bees. There’s no central mass, but each star orbits the common center of mass, and because this is an n-body problem, those orbits can be very loopy–to say the least. You’re talking about thousands of bodies–all moving independently of each other. Any planetary system would probably be disrupted by passing stars.

      It’s surprising that these objects have lasted so long, since close encounters in the cluster should toss either or both stars out of the cluster.

      How and why these clusters formed is still a mystery. All galaxies seem to have lots of them, so their presence is a normal process in the formation of galaxies.


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