NASA has revealed a grainy photo of Pluto’s dark side six years after it was captured by its New Horizons spacecraft.
The image — taken in July 2015 when Pluto was 3 billion miles from Earth — shows the portion of the dwarf planet’s landscape not directly illuminated by sunlight.
Researchers were able to generate the image using 360 images New Horizons captured as it looked back over Pluto’s southern hemisphere during its flight.
The image used light reflected from Charon, the largest of Pluto’s five moons.
The image reveals a large and “strikingly bright” region halfway between Pluto’s south pole and its equator, which may be a deposit of nitrogen or methane ice, similar to Pluto’s icy “heart” on the other side.
The image shows Pluto’s dark side surrounded by a bright ring of sunlight scattered by atmospheric nebula. Researchers from the New Horizons team were able to generate this image using 360 images New Horizons captured as it looked back over Pluto’s southern hemisphere.
PLUTO: FAST FACTS
Discovered by: Clyde W. Tombaugh
discovery dat: February 18, 1930
Surface temperature: -387°F (-232°C)
job period: 247,92065 Earth years
job distance: 5,874,000,000 km (39.26 AU)
known moons: 5 (Charon, Nix, Hydra, Kerberos and Styx)
Diameter: 1,471 miles (2,368 km)
Mass: 13,050,000,000,000 billion kg (0.00218 x Earth)
“By a surprising coincidence, the amount of light from Charon on Pluto is close to that from the moon on Earth, in the same phase for each,” said Tod Lauer, an astronomer at the National Science Foundation’s National Optical Infrared Astronomy Research Observatory in Tucson. , Arizona.
“At the time, Charon’s illumination on Pluto was comparable to that of our own moon on Earth in the first quarter phase.”
Pluto — which is smaller than Earth’s moon — is a complex world of frozen plains and icebergs the size of the Rockies.
Once considered the ninth planet, Pluto is the largest member of the Kuiper Belt and the best known of a new class of worlds called dwarf planets.
NASA’s New Horizons spacecraft was launched in January 2006 and made history by returning the first close-up images of Pluto and its moons over the next decade.
After flying within 7,800 miles (12,550 kilometers) of Pluto’s icy surface on July 14, 2015, New Horizons advanced toward the Kuiper Belt at a rapid nine miles per second.
As it left Pluto, the spacecraft looked back at the dwarf planet and captured a series of images of its dark side, illuminated by the distant sun.
Although Pluto’s hazy atmosphere stood out as a brilliant ring of light, the dark side itself was, of course, hidden.
An incomplete view of Pluto’s crescent. Although Pluto’s hazy atmosphere stood out as a dazzling ring of light, the dark side itself was, of course, hidden
Fortunately, part of Pluto’s dark southern hemisphere was illuminated by the faint sunlight bouncing off the icy surface of Pluto’s largest moon, Charon, which is about the size of Texas.
PLUTO’S ATMOSPHERE DISAPPEARS, STUDY FINDS
Pluto’s atmosphere disappears as it moves farther from the sun, a new study has revealed.
Pluto takes 248 Earth years to complete a single orbit around the sun, and its distance ranges from its closest point from 30 AU (2.7 billion miles) to 50 AU (4.6 billion miles).
Researchers have deployed telescopes in several locations in the US and Mexico to observe the distant world as it passed in front of a star, briefly illuminating the dwarf planet from background and revealing its small, nitrogen-rich atmosphere.
Their observations suggest that as Pluto moves farther from the sun in its long orbit, it gets colder and its nitrogen refreezes on the surface.
Read more: Pluto’s atmosphere is disappearing, study finds
That bit of “Charon light” was just enough for researchers to discover details of Pluto’s southern hemisphere that couldn’t be obtained any other way.
However, finding details on Pluto’s surface in dim moonlight wasn’t easy — which is part of the reason the image was released more than six years after the flyby.
Looking back at Pluto, the scattered light from the Sun (which was almost directly behind Pluto at the time) produced a complex pattern of backlight that was 1000 times stronger than the signal produced by the light reflected from Charon.
In addition, the bright ring of atmospheric haze surrounding Pluto itself was heavily overexposed, producing additional artifacts in the images.
“The problem was a lot like trying to read a street sign through a dirty windshield while driving toward the setting sun without a visor,” said John Spencer, a New Horizons co-researcher and researcher at the Southwest Research Institute in Boulder. Colorado.
The combination of 360 images of Pluto’s dark side and another 360 images taken with the same geometry but without Pluto in the image was necessary to produce the final image, which consists only of the signal produced by Charon-reflected light.
Looking at the image, Pluto’s south pole and the area around it appear to be covered with a dark material, which contrasts sharply with the paler surface of Pluto’s northern hemisphere.
The researchers suspect the difference may be a result of Pluto recently completing its austral summer (which ended 15 years before the flyby).
Pluto takes 248 Earth years to orbit the sun, so the seasons can last for decades.
A chart overlay shows Pluto’s physical extent (black circle) and the limit of Charon’s illumination (solid, vertical gold line) when New Horizons captured the images. The dotted gold lines represent latitudes, with Pluto’s south pole at the bottom. The extremely high contrast in the images reveals a large, strikingly bright region halfway between Pluto’s south pole and its equator (third dotted line from below). The team suspects it to be a deposit of nitrogen or methane ice, similar to Pluto’s icy “heart” on the other side. The dark crescent to the west (left) is where neither sunlight nor Charon light fell
The ice-covered “heart” of Pluto is clearly visible in this false-color image from NASA’s New Horizons spacecraft. The left roughly oval lobe on Pluto’s surface is the basin informally called Sputnik Planitia. Pluto’s largest moon, Charon appears at the top left
Pluto has a thin atmosphere of nitrogen, methane and carbon monoxide.
Over the summer, the team suggests that nitrogen and methane ice in the south may have turned directly from solids to vapor, as dark mist particles settled over the region.
Carly Howett of the Southwest Research Institute, who is part of the New Horizons team but was not involved in this study, said: science news that the image may help understand how Pluto’s nitrogen atmosphere varies through the seasons.
Pluto’s atmosphere thickens as more nitrogen ice evaporates, but if too much nitrogen freezes to the ground, the atmosphere can collapse.
Future Earth-based instruments could eventually verify the team’s image and confirm other suspicions, but that would require Pluto’s southern hemisphere to be in sunlight — something that won’t happen for nearly 100 years.
“The easiest way to confirm our ideas is to send a follow-up mission,” Lauer said.
The researchers shared their view and scientific interpretation of it in a study published by the American Astronomical Society in the The Planetary Science Magazine.
Why is Pluto not a planet, but a dwarf planet?
Pluto and the Sputnik Plantia Formation
In 2006, the International Astronomical Union, a global group of astronomy experts, established a definition of a planet that should “clear” its orbit, or in other words, be the greatest gravity in its orbit.
Since Neptune’s gravity affects its neighboring planet Pluto, and Pluto shares its orbit with frozen gases and objects in the Kuiper belt, that meant Pluto had no planetary status.
Pluto was downgraded from its definition of a planet to a dwarf planet, which, despite its name, is not a “planet” as defined by the IAU.
The main difference between ‘dwarf planet’ and ‘planet’ is that the latter does not dominate its region of space.
Before 2006, there was never a formal definition of what a planet was.
Scientists argue that this means that Pluto’s degradation is unjust and unreasonable.
“Just so you know, in my opinion Pluto is a planet,” said NASA administrator Jim Bridenstine.