Hubble Space Telescope captures 'mirror image' view of distant galaxy

Jan 27, 2020
Galaxy SGAS J143845+145407 is located in the northern constellation Boötes*. Light from this distant galaxy is distorted by the gravitational pull of an intervening astronomical object when viewed by the Hubble Space Telescope. (Image credit: ESA/Hubble & NASA, J. Rigby)

NASA's venerable space telescope is seeing double in a stunning new image of a distant galaxy.

The new image from the Hubble Space Telescope captures a galaxy named SGAS J143845+145407, located in the northern constellation Boötes — one of the largest constellations in the sky. The mirror image of the galaxy at the center of this new photo is the result of strong gravitational lensing, which is an astronomical phenomenon that can warp, magnify or even duplicate the appearance of distant galaxies.

"Gravitational lensing occurs when a massive celestial body — such as a galaxy cluster — causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, as if by a lens," according to a statement from the European Space Agency (ESA). "Appropriately, the body causing the light to curve is called a gravitational lens, and the distorted background object is referred to as being 'lensed.'"

At the center of the new Hubble image, the bright light emanating from SGAS J143845+145407 appears as an arc or ring around either side of the object that lies between the distant galaxy and the space telescope. The image also captures several other galaxies and celestial objects scattered across space.

The light from SGAS J143845+145407 traveled around 6.9 billion years to reach us. That's about half the current age of the Universe. The cluster's light traveled about 2.8 billion years.

SGAS J143845+145407 is scientifically interesting because it's a luminous infrared galaxy, glowing relatively brightly due to high star formation activity. Studying galaxies like it can help scientists understand star formation and how it has changed throughout the Universe's history; for this kind of work, gravitational lenses can be invaluable.

Using the gravitational lens, scientists were recently able to reconstruct the distribution of star formation in SGAS J143845+145407, and study the details of the process. They found that the galaxy is pretty typical of its type, which information will be able to help contextualize and characterize other galaxies.

Hubble has a special flair for detecting lensed galaxies. The telescope's sensitivity and crystal-clear vision let it see faint and distant gravitational lenses that ground-based telescopes cannot detect because of the blurring effect of Earth's atmosphere. Hubble was the first telescope to resolve details within lensed images of galaxies and is capable of imaging both their shape and internal structure.

This particular lensed galaxy is from a set of Hubble observations that take advantage of gravitational lensing to peer inside galaxies in the early universe. The lensing reveals details that allow astronomers to better understand star formation in early galaxies, which gives scientists insight into how the overall evolution of galaxies unfolded. SGAS J143845+145407 has a red shift of 0.816.

Hubble is equipped with sensitive scientific instruments that allow it to capture faint and distant gravitational lenses that ground-based telescopes are not able to detect due to blurring caused by Earth's atmosphere.

Gravitational lensing also allows astronomers to observe objects that would otherwise be too far away or too faint to be seen. The distortion caused by the foreground object acts as a natural magnifying glass, zooming in on more distant celestial objects. Hubble is able to capture the light from those more distant objects to determine their shape and internal structure, according to the statement from ESA.

The recent image of galaxy SGAS J143845+145407 was taken as part of a larger Hubble initiative to study galaxies of the early universe using gravitational lensing to examine the galaxies up close.

"The lensing reveals details of distant galaxies that would otherwise be unobtainable, and this allows astronomers to determine star formation in early galaxies," ESA officials said in the statement. "This in turn gives scientists a better insight into how the overall evolution of galaxies has unfolded."

Webb is expected to reveal even more details, but Hubble revolutionized the study of lensed galaxies. Its observations were the first to resolve details inside lensed galaxies, giving scientists an incredible new window into the early Universe.



* Boötes constellation location in the NW sky:

bootes found.jpeg

Boötes is the 13th largest constellation in the night sky, occupying an area of 907 square degrees. It is located in the third quadrant of the northern hemisphere (NQ3) and can be seen at latitudes between +90° and -50°. The neighboring constellations are Canes Venatici, Coma Berenices, Corona Borealis, and Draco the Dragon.

The constellation’s name comes from the Greek word Βοώτης, Boōtēs, which means ox driver, plowman, or herdsman. The correct pronunciation is /boʊˈoʊtɨs/, with each ‘o’ pronounced separately and stress on the second syllable. Boötes was first catalogued by the Greek astronomer Ptolemy in the 2nd century.

The constellation is home to the contrasting double star Izar and Arcturus, the brightest star in the northern celestial hemisphere and third individual brightest star in the sky, after Sirius in Canis Major and Canopus in Carina constellation.

Boötes has five stars with known planets and does not contain any Messier objects. The brightest star in the constellation is Arcturus, Alpha Boötis, which is also the third brightest star in the night sky. There are three meteor showers associated with the constellation Boötes: the January Bootids, the June Bootids, and the Quadrantids.

Boötes contains 10 named stars. The star names approved by the International Astronomical Union (IAU) are Alkalurops, Arcalís, Arcturus, Izar, Merga, Muphrid, Nekkar, Nikawiy, Seginus, and Xuange.


Galaxy SGAS J143845+145407 is one of the Hubble Space Telescope's most interesting finds. The mass of the intervening galactic cluster has created a mirror image of SGAS J143845+145407, the orange appearing due to the galaxy's red shift. It will be interesting when the James Webb Space Telescope explores this anomaly further.