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Celestial Object Past Pluto Looks Like A Snowman: NASA

It's neither a comet nor an asteroid, according to Stern, but rather "a primordial planetesimal."

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NASA, Pluto
This image made available by NASA on Jan. 2, 2019, shows images with separate color and detail information, and a composited image of both, showing Ultima Thule, about 1 billion miles beyond Pluto. VOA

A NASA spacecraft 4 billion miles from Earth yielded its first close-up pictures Wednesday of the most distant celestial object ever explored, depicting what looks like a reddish snowman.

Ultima Thule, as the small, icy object has been dubbed, was found to consist of two fused-together spheres, one of them three times bigger than the other, extending about 21 miles (33 kilometers) in length.

NASA’s New Horizons, the spacecraft that sent back pictures of Pluto 3-plus years ago, swept past the ancient, mysterious object early on New Year’s Day. It is 1 billion miles (1.6 billion kilometers) beyond Pluto.

On Tuesday, based on early, fuzzy images taken the day before, scientists said Ultima Thule resembled a bowling pin. But when better, closer pictures arrived, a new consensus emerged Wednesday.

“The bowling pin is gone. It’s a snowman!” lead scientist Alan Stern informed the world from Johns Hopkins University’s Applied Physics Laboratory , home to Mission Control. The bowling pin image is “so 2018,” joked Stern, who is with the Southwest Research Institute.

NASA, earth
New Horizons project scientist Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory, speaks about new data received from the New Horizons spacecraft during a press conference after the spacecraft completed a flyby of Ultima Thule, Jan. 1, 2019. VOA

The celestial body was nicknamed Ultima Thule — meaning “beyond the known world” — before scientists could say for sure whether it was one object or two. With the arrival of the photos, they are now calling the bigger sphere Ultima and the smaller one Thule.

Thule is estimated to be 9 miles (14 kilometers) across, while Ultima is thought to be 12 miles (19 kilometers).

Scientist Jeff Moore of NASA’s Ames Research Center said the two spheres formed when icy, pebble-size pieces coalesced in space billions of years ago. Then the spheres slowly spiraled closer to each other until they gently touched — as slowly as parking a car here on Earth at just a mile or two per hour — and stuck together.

Despite the slender connection point, the two lobes are “soundly bound” together, according to Moore.

 

Pluto, NASA, new horizons
This illustration provided by NASA shows the New Horizons spacecraft. NASA launched the probe in 2006; it’s about the size of a baby grand piano. VOA

Scientists have ascertained that the object takes about 15 hours to make a full rotation. If it were spinning fast — say, one rotation every three or four hours — the two spheres would rip apart.

Stern noted that the team has received less than 1 percent of all the data stored aboard New Horizons. It will take nearly two years to get it all.

The two-lobed object is what is known as a “contact binary.” It is the first contact binary NASA has ever explored. Having formed 4.5 billion years ago, when the solar system taking shape, it is also the most primitive object seen up close like this.

About the size of a city, Ultima Thule has a mottled appearance and is the color of dull brick, probably because of the effects of radiation bombarding the icy surface, with brighter and darker regions.

Both spheres are similarly red, while the barely perceptible neck connecting the two lobes is noticeably less red, probably because of particles falling down the steep slopes into that area.

Pluto, NASA, new horizons
New Horizons team members are seen during a press conference prior to the flyby of Ultima Thule by the New Horizons spacecraft, Dec. 31, 2018, at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. VOA

So far, no moons or rings have been detected. And scientists said there were no obvious impact craters in the latest photos but a few apparent “divots” and suggestions of hills and ridges. But better images should yield definitive answers in the days and weeks ahead.

Clues about the surface composition of Ultima Thule should start rolling in by Thursday. Scientists believe the icy exterior is probably a mix of water, methane and nitrogen, among other things.

The snowman picture was taken a half-hour before the spacecraft’s closest approach early Tuesday, from a distance of about 18,000 miles (28,000 kilometers).

Ultima Thule is an exquisite time machine — the most primitive object ever seen close up — that should provide clues to the origins of our solar system.

Also Read: NASA’s New Horizon Set Out To Make History

It’s neither a comet nor an asteroid, according to Stern, but rather “a primordial planetesimal.” Unlike comets and other objects that have been altered by the sun over time, Ultima Thule is in its pure, original state: It’s been in the deep-freeze Kuiper Belt on the fringes of our solar system from the beginning.

“This thing was born somewhere between 99 percent and 99.9 percent of the way back to T-zero (liftoff) in our solar system, really amazing,” Stern said. He added: “We’ve never seen anything like this before. It’s not fish or fowl. It’s something that’s completely different.”

Still, he said, when all the data comes in, “there are going to be mysteries of Ultima Thule that we can’t figure out.” (VOA)

Next Story

Asteroids Are Falling On Earth’s Surface Twice As Often: Study

This enhanced impact rate poses a threat for the next mass extinction event.

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Asteroids
This Dec. 29, 1968, photo made available by NASA shows craters on the moon. For the past 290 million years, giant rocks from space have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study. VOA

Giant rocks from space are falling from the sky more than they used to, but don’t worry.

For the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the previous 700 million years, according to a new study in Thursday’s journal Science.

But no need to cast a wary glance up. Asteroids still only smack Earth on average every million or few million years, even with the increased crash rate. NASA’s list of potential big space rock crashes shows no pending major threats. The biggest known risk is a 4,200-foot (1.3-km) wide asteroid with a 99.988 percent chance that it will miss Earth when it whizzes very near here in 861 years.

Tell that to the dinosaurs. Most scientists think dinosaurs and a lot of other species went extinct after a huge space rock crashed into Central America about 65 million years ago.

Earth, Asteroids
Taurids meteor shower lights up the sky. The risk of asteroids hitting the Earth has grown over the years. Wikimedia

“It’s just a game of probabilities,” said study lead author Sara Mazrouei, a University of Toronto planetary scientist. “These events are still rare and far between that I’m not too worried about it.”

Mazrouei and colleagues in the United Kingdom and United States compiled a list of impact craters on Earth and the moon that were larger than 12 miles (20 km) wide and came up with the dates of them. It takes a space rock that’s half a mile (800 meters) wide to create holes that big.

The team counted 29 craters that were no older than 290 million years and nine between 291 million years and 650 million years old.

But we can see relatively few big craters on Earth because the planet is more than 70 percent ocean and past glaciers smoothed out some holes, said University of Toronto planetary scientist Rebecca Ghent, a study co-author.

Earth, Asteroids
These rocks were rare survivors from a very different time on Earth. Pixabay

Extrapolating for what can’t be seen brings the total to about 260 space crashes on Earth in the last 290 million years. Adding in other factors, the science team determined that the current space crash rate is 2.6 times more than the previous 700 million years.

Craters older than 650 million years are mostly wiped off on Earth by glacial forces so the scientists used impact craters on the nearby moon as a stand-in for holes between 650 million and 1 billion years old. The moon is a good guide for estimating Earth crashes, because it is close enough to be in the same bombardment path and its craters last longer.

Mixed reactions

So what happened nearly 300 million years ago?

“Perhaps an asteroid family was broken up in the asteroid belt,” Mazrouei speculated. The space rocks then headed toward the Earth and moon, and the planet got slightly more because it is a bigger target and it has higher gravity, Ghent said.

Oldest known asteroid family
An asteroid family. Wikimedia

Outside scientists are split about the research. Jay Melosh at Purdue said he found the number of craters too small to come to a reasonable conclusion, but Harvard’s Avi Loeb said the case was convincing.

Also Read: Newly Discovered Super-Earth Exoplanet May Sustain Primitive Life

Humans might not have emerged without mass extinctions from space rocks about 250 million and 65 million years ago, Loeb said in an email, adding, “but this enhanced impact rate poses a threat for the next mass extinction event, which we should watch for and attempt to avoid with the aid of technology.”

“This demonstrates how arbitrary and fragile human life is,” Loeb wrote. (VOA)