Great Attractor
Encyclopedia
Gravity anomaly
A gravity anomaly is the difference between the observed acceleration of Earth's gravity and a value predicted from a model.-Geodesy and geophysics:...
in intergalactic space within the range of the Centaurus Supercluster that reveals the existence of a localised concentration of mass equivalent to tens of thousands of Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
s, observable by its effect on the motion of galaxies and their associated clusters over a region hundreds of millions of light years
Light Years
Light Years is the seventh studio album by Australian recording artist Kylie Minogue. It was released on 25 September 2000 by Parlophone and Mushroom Records. The album's style was indicative of her return to "mainstream pop dance tunes"....
across.
These galaxies are all redshift
Redshift
In physics , redshift happens when light seen coming from an object is proportionally increased in wavelength, or shifted to the red end of the spectrum...
ed, in accordance with the Hubble Flow, indicating that they are receding relative to us and to each other, but the variations in their redshift are sufficient to reveal the existence of the anomaly. The variations in their redshifts are known as peculiar velocities
Peculiar velocity
Peculiar motion or peculiar velocity refers to the true velocity of an object, relative to a rest frame.-Galactic astronomy:In galactic astronomy, the term peculiar motion refers to the motion of an object through space.Local objects are usually related in terms of proper motion and radial...
, and cover a range from about +700 km/s to −700 km/s, depending on the angular deviation from the direction to the Great Attractor.
Location
The first indications of a deviation from uniform expansion of the universe were reported in 1973 and again in 1978. The location of the Great Attractor was finally determined in 1986, and is situated at a distance of somewhere between 150 and 250 Mly (million light years) (47–79MpcParsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
) (the latter being the most recent estimate) from the Milky Way, in the direction of the constellations Hydra
Hydra (constellation)
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake...
and Centaurus
Centaurus
Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...
. While objects in that direction lie in the Zone of Avoidance
Zone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
(the part of the night sky obscured by the Milky Way galaxy
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
) and are thus difficult to study with visible wavelengths, X-ray observations have revealed that the region of space is dominated by the Norma cluster (ACO 3627)
Norma cluster
The Norma Cluster is a rich cluster of galaxies located near the center of the Great Attractor. Although it is both nearby and bright, it is difficult to observe because it is located in the Zone of Avoidance, a region near the plane of the Milky Way. Consequently, the cluster is severely...
, a massive cluster of galaxies, containing a preponderance of large, old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves
Radio waves
Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers. Like all other electromagnetic waves,...
.
Debate over apparent mass
In 1992, much of the apparent signal of the Great Attractor was attributed to the effect of Malmquist BiasMalmquist bias
The Malmquist bias refers to an effect in observational astronomy which leads to the preferential detection of intrinsically bright objects. It was first popularized in 1922 by Swedish astronomer Gunnar Malmquist , who then greatly elaborated upon this work in 1925...
. In 2005, astronomers conducting an X-ray survey of part of the sky known as the Clusters in the Zone of Avoidance
Zone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
(CIZA) project reported that the Great Attractor was actually only one tenth the mass that scientists had originally estimated. The survey also confirmed earlier theories that the Milky Way galaxy was in fact being pulled towards a much more massive cluster of galaxies near the Shapley Supercluster
Shapley Supercluster
The Shapley Supercluster or Shapley Concentration is the largest concentration of galaxies in our nearby universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears as a striking overdensity in the distribution of...
which lies beyond the Great Attractor.
In fiction
The Great Attractor is mentioned in the "Pip and Flinx" series by novelist Alan Dean FosterAlan Dean Foster
Alan Dean Foster is an American author of fantasy and science fiction. He currently resides in Prescott, Arizona, with his wife, and is also known for his novelizations of film scripts...
, in the book Flinx's Folly
Flinx's Folly
Flinx's Folly is a science fiction novel written by Alan Dean Foster. The book is the eighth chronologically in the Pip and Flinx series.-Plot summary:...
. The Great Attractor is referenced as an attempt of an ancient alien race to create something with enough gravitational pull to move the Milky Way, among other galaxies.
It is also a major plot point in the Xeelee Sequence
Xeelee Sequence
The Xeelee Sequence is a series of novels and short stories by British science fiction author Stephen Baxter. The novels span several billions of years, describing the future expansion of Mankind, its war with its arch-nemesis , and the Xeelee's own war with dark matter entities called photino birds...
series of books by Stephen Baxter
Stephen Baxter
Stephen Baxter is a prolific British hard science fiction author. He has degrees in mathematics and engineering.- Writing style :...
, specifically in the book Ring where it is described as a cosmic string
Cosmic string
Cosmic strings are hypothetical 1-dimensional topological defects which may have formed during a symmetry breaking phase transition in the early universe when the topology of the vacuum manifold associated to this symmetry breaking is not simply connected. It is expected that at least one string...
, artificially made into a loop creating the phenomenon of the Great Attractor.
In the movie Men in Black
Men in Black (film)
Men in Black is a 1997 science fiction comedy film directed by Barry Sonnenfeld, starring Tommy Lee Jones, Will Smith and Vincent D'Onofrio. The film was based on the Men in Black comic book series by Lowell Cunningham, originally published by Marvel Comics. The film featured the creature effects...
, the Great Attractor is described as a sentient being who, in addition to distorting the arrangement of nearby galaxies, caused the New York City blackout of 1977
New York City blackout of 1977
The New York City blackout of 1977 was an electricity blackout affected most of New York City from July 13, 1977 to July 14, 1977. The only neighborhoods in New York City that were not affected were in southern Queens, and neighborhoods of the Rockaways, which are part of the Long Island Lighting...
with a device which is now safely stored in the MIB's headquarters.
The Great Attractor is mentioned by the name "Azrael" in Reaper Man
Reaper Man
Reaper Man is a Discworld novel by Terry Pratchett. Published in 1991, it is the 11th Discworld novel and the second to focus on Death. The title is a reference to Alex Cox's cult movie Repo Man.-Plot:...
by Terry Pratchett
Terry Pratchett
Sir Terence David John "Terry" Pratchett, OBE is an English novelist, known for his frequently comical work in the fantasy genre. He is best known for his popular and long-running Discworld series of comic fantasy novels...
(1991), as the ultimate death of the Discworld
Discworld (world)
The Discworld is the fictional setting for all of Terry Pratchett's Discworld fantasy novels. It consists of a large disc resting on the backs of four huge elephants which are in turn standing on the back of an enormous turtle, named Great A'Tuin as it slowly swims...
.