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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 Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate overlapping fields of view taken over 10 years of Hubble observing—a challenge to stitch together over such a large area. The mosaic image is made up of at least 2.5 billion pixels. Hubble resolves an estimated 200 million stars that are hotter than our Sun, but still a fraction of the galaxy’s total estimated stellar population.
Interesting regions include: (a) Clusters of bright blue stars embedded within the galaxy, background galaxies seen much farther away, and photo-bombing by a couple bright foreground stars that are actually inside our Milky Way; (b) NGC 206 the most conspicuous star cloud in Andromeda; (c) A young cluster of blue newborn stars; (d) The satellite galaxy M32, that may be the residual core of a galaxy that once collided with Andromeda; (e) Dark dust lanes across myriad stars.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.00:42
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.+41:15
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Andromeda
- DistanceDistanceThe 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
- InstrumentInstrumentThe science instrument used to produce the data.ACS
- FiltersFiltersThe camera filters that were used in the science observations.F475W, F814W
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.M31, Andromeda Galaxy, NGC 224
- Object DescriptionObject DescriptionThe type of astronomical object.Spiral Galaxy
- Release DateJanuary 16, 2025
- Science ReleaseNASA’s Hubble Traces Hidden History of Andromeda Galaxy
- CreditNASA, ESA, Benjamin Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern); Image Processing: Joseph DePasquale (STScI)
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)
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
NASA, ESA, Benjamin Williams (UWashington), Zhuo Chen (UWashington), L. Clifton Johnson (Northwestern)
Joseph DePasquale (STScI)