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Hubble M31 PHAT+PHAST Mosaic

The Andromeda galaxy, a spiral galaxy, spreads across the width. It is tilted nearly edge-on to our line of sight so that it appears as an extreme oval on its side. The borders of the galaxy are jagged because the image is a mosaic of smaller, square images. The outer edges are blue, while the inner two-thirds are yellowish with a bright, central core. Dark, dusty filamentary clouds wrap around the outer half of the galaxy’s disk. At 10 o'clock, a smaller dwarf elliptical galaxy forms a fuzzy, yellow blob. Hubble's sharp vision distinguishes about 200 million stars within the image. The background of space is black. There are what appears to be steps toward the bottom, mainly toward the middle, which indicates where no data were taken.

This is the largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. It took over 10 years to make this vast and colorful portrait of the galaxy, requiring over 600 Hubble overlapping snapshots that were challenging to stitch together. The galaxy is so close to us, that in angular size it is six times the apparent diameter of the full Moon, and can be seen with the unaided eye. For Hubble's pinpoint view, that's a lot of celestial real estate to cover. This stunning, colorful mosaic captures the glow of 200 million stars. That's still a fraction of Andromeda's population. And the stars are spread across about 2.5 billion pixels. The detailed look at the resolved stars will help astronomers piece together the galaxy's past history that includes mergers with smaller satellite galaxies.

 

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    00:42
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    +41:15
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Andromeda
  • Distance
    DistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.
    2.5 million light-years

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.

    Data of M31 were obtained from the HST PHAT and PHAST Treasury proposals: P.I. J. Dalcanton and B. Williams (University of Washington) et al. 12058, 12073, 12109, 12107, 12074, 12105, 12113, 12075, 12057, 12111, 12115, 12071, 12114, 12072, 12056, 12106, 12059, 12108, 12110, 12112, 12055, 12076, 12070, 16778, 16778, 16796, 16796, 16797, 16797, 16798, 16798, 16799, 16799, 16800, 16800, 16801

  • Instrument
    InstrumentThe science instrument used to produce the data.
    ACS
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    July 2010 - Dec 2022
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F475W, F814W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    M31, Andromeda Galaxy, NGC 224
  • Object Description
    Object DescriptionThe type of astronomical object.
    Spiral Galaxy
  • Release Date
    January 16, 2025
  • Science Release
    NASA’s Hubble Traces Hidden History of Andromeda Galaxy
    Read the release
  • Credit
    NASA, ESA, Benjamin Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)

Downloads

  • Half Res (For Display), 84416 × 19739
    png (965.84 MB)
  • Quarter Res (For Display), 42208 × 9870
    png (748.98 MB)
  • Quarter Res (For Print), 42208 × 9870
    tif (992.82 MB)
  • Reduced Res 1, 21104 × 4935
    png (187.15 MB)
  • Reduced Res 2, 10552 × 2468
    png (43.45 MB)
  • 1997 × 467
    jpg (311.35 KB)
The Andromeda galaxy, a spiral galaxy, spreads across the width. It is tilted nearly edge-on to our line of sight so that it appears as an extreme oval on its side. The borders of the galaxy are jagged because the image is a mosaic of smaller, square images. The outer edges are blue, while the inner two-thirds are yellowish with a bright, central core. Dark, dusty filamentary clouds wrap around the outer half of the galaxy’s disk. At 10 o'clock, a smaller dwarf elliptical galaxy forms a fuzzy, yellow blob. Hubble's sharp vision distinguishes about 200 million stars within the image. The background of space is black. There are what appears to be steps toward the bottom, mainly toward the middle, which indicates where no data were taken.
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

This image is a composite of separate exposures acquired by the ACS instrument on the Hubble Space Telescope. Several filters were used to sample broad wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Blue: F475W (g) Yellow: F814W (I)

Compass and Scale
Compass and ScaleAn astronomical image with a scale that shows how large an object is on the sky, a compass that shows how the object is oriented on the sky, and the filters with which the image was made.

Related Images & Videos

Photo mosaic of Andromeda galaxy and five regions of interest. A spiral galaxy spreads across the width. It’s tilted nearly edge-on to our line of sight, appearing as an extreme oval on its side. Its borders are jagged because the image is a mosaic of smaller, square images. The outer edges are blue, while the inner two-thirds are yellowish with a bright, central core. Dark, dusty clouds wrap around the outer half of the galaxy’s disk. At 10 o'clock, a smaller dwarf elliptical galaxy forms a fuzzy, yellow blob. There are about 200 million stars within the image. The background of space is black. There are what appears to be steps toward the bottom, mainly toward the middle, which indicates where no data were taken. Interesting regions: (a) Clusters of bright blue stars embedded within the galaxy; background galaxies seen much farther away; (b) NGC 206, a concentration of bright blue stars; (c) A young cluster of blue newborn stars; (d) The satellite galaxy M32; (e) Dark dust lanes across myriad yellow stars.

Compass and Scale Image of M31 PHAT+PHAST Mosaic

This is the largest photomosaic ever made by the Hubble Space Telescope. The target is the vast Andromeda galaxy that is only 2.5 million light-years from Earth, making it the nearest galaxy to our own Milky Way. Andromeda is seen almost edge-on, tilted by 77 degrees relative to...

This video opens with the largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. The spiral disk galaxy is inclined to our view, making it look elliptical. Young blue stars are around the outer rim. Yellowish older stars are toward the center. The bright hub of the galaxy looks like the center of a fried egg. It took over 10 years to make this vast and colorful portrait of the galaxy, requiring over 600 Hubble snapshots. This stunning mosaic captures the glow of 200 million stars. The camera zooms into the central portion of the galaxy, resolving a sea of myriad older stars. The camera pans along the galaxy's vast disk which is over 200,000 light-years across. The view is etched with dark dust clouds. The stellar population looks bluer as we move toward the galaxy's outer rim, rich in bright blue star clusters.

Andromeda M31 PHAST Mosaic Video

This video opens with the largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. It took over 10 years to make this vast and colorful portrait of the galaxy,...

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Details

Last Updated
Mar 18, 2025
Contact
Media

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov

Science Credit

NASA, ESA, Benjamin Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern)

Image Processing Credit

Joseph DePasquale (STScI)

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