Tag: Astronomers

Astronomers Have Found A New Crop Of Moons Around Jupiter, And One Of Them Is A Weirdo

Ten more moons have been confirmed to orbit around Jupiter, bringing the planet’s total known satellite count to 79.

That’s the highest number of moons of any planet in the Solar System. And these newly discovered space rocks are giving astronomers insight as to why the Jupiter system looks like it does today.

Astronomers at Carnegie Institution for Science first found these moons in March 2017, along with two others that were already confirmed in June of last year.

The team initially found all 12 moons using the Blanco 4-meter telescope in Chile, though finding these objects wasn’t their main goal.

Instead, they were searching for incredibly distant small objects — or even planets — that might be lurking in our Solar System beyond Pluto.

But as they searched for these fringe space rocks, they decided to take a peek at what might be lurking around Jupiter at the same time.

Now, the moons they found have been observed multiple times, and their exact orbits have been submitted for approval from the International Astronomical Union, which officially recognizes celestial bodies.

These moons are all pretty tiny, ranging between less than a mile and nearly two miles wide. And they break down into three different types. Two orbit closer to Jupiter, moving in the same direction that the planet spins.

Farther out from those, about 15.5 million miles from the planet, there are nine that revolve in the opposite direction, moving against Jupiter’s rotation.

But in this same distant region, one strange moon that astronomers are calling Valetudo is moving with Jupiter’s spin, like the two inner moons.

That means it’s going in the opposite direction of all the other moons in the same area. “It’s basically driving down the highway in the wrong direction,” Scott Sheppard, an astronomer at Carnegie who led the discovery team said.

That’s a very unstable situation. Head-on collisions are likely to happen in that situation.

Valetudo isn’t the only moon of Jupiter that acts this way. Another moon called Carpo also orbits far out from Jupiter, moving in the opposite direction of many other moons in the area.

The small dot between the yellow lines in these photographs is the newly discovered moon Valetudo.

However, Valetudo orbits much farther away than Carpo, and it may actually be the smallest moon Jupiter has.

Now with this discovery, astronomers think it’s good evidence that moon-on-moon collisions have happened in Jupiter’s past, and these are responsible for the lunar landscape around the planet today.

Valetudo, at just 1 kilometer across, is probably the last remnant of a much larger moon that’s been ground down into dust over time,” says Sheppard.

Finding moons around Jupiter can be tough. As the biggest planet in our Solar System, it has a very large area of influence, so there’s a lot of space where moons could potentially be.

It’s difficult to search that area in a timely manner with a telescope. “It’s like looking through a straw, and you’re just covering as many points around Jupiter as you can looking for these things,” says Sheppard.

And since Jupiter is so large, it reflects a whole lot of light. That means there can be a lot of glare when searching for super faint moons around the planet.

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Pass it on: Popular Science

Weird Space Rock Provides More Evidence For Mysterious ‘Planet Nine’

The solar system just got a bit stranger. As astronomers continue their ongoing quest to find the elusive Planet Nine, a team found a space rock that lends credence to the idea that a huge super-Earth planet really exists in the outer reaches of our solar system.

The newfound asteroid, called 2015 BP519, adds to a growing body of evidence about little worlds in the solar system being perturbed by something big.

Astronomers detailed its discovery and description in a new paper, adding that the bizarre angle of its orbit gives more weight to the idea that a big planet is out there — somewhere — tugging on the asteroid’s path around the sun.

Following up on the discovery, Quanta Magazine recently published an article surveying several astrophysicists who specialize in studying small worlds, including the discoverers of 2015 BP519.

While not everybody agreed that Planet Nine was responsible for the strange orbit, the overwhelming majority agreed the new discovery gives more credence to the idea.

The second you put Planet Nine in the simulations, not only can you form objects like this object, but you absolutely do,” lead author Juliette Becker, a graduate student at the University of Michigan, told Quanta.

It’s not the first time Planet Nine was blamed for pushing an object around.

Back in 2014, before Planet Nine was officially hypothesized, astronomers Scott Sheppard and Chadwick Trujillo noticed orbital irregularities in several small bodies beyond Neptune’s orbit.

These included dwarf planet Sedna, a newfound object called 2012 VP113, and several other trans-Neptunian objects (TNOs).

Then, in January 2016, astronomers Konstantin Batygin and Mike Brown saw more evidence of TNOs with perturbed orbits.

They were the ones who first gave “Planet Nine” a name, size and distance. They suggested that the mysterious planet could be 10 times more massive than Earth, located 600 astronomical units (AU) from the sun.

A flood of studies followed about TNOs and how Planet Nine might have affected their orbits; the following summary is just a sampling.

Not all teams were enthusiastic, with one group from the Outer Solar System Origins Survey (OSSOS) cautioning that many of these surveys could be just observational bias.

But astronomers persisted, with Sheppard and Trujillo discovering at least two new TNOs possibly affected by Planet Nine. Another study showed Planet Nine perhaps influenced the tilt of planets in our solar system.

And in 2017, astronomers from the University of Madrid in Spain found peculiarities in the orbits of 22 “extreme” TNOs that orbit the sun that could also be explained by a large, distant body exerting gravitational influence.

By October 2017, Batygin said, there were at least five different lines of evidence that suggest the existence of the planet.

“If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them,” he said in a statement.

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Pass it on: Popular Science

Mysterious Dark Matter May Not Always Have Been Dark

The nature of dark matter is currently one of the greatest mysteries in science. The invisible substance — which is detectable via its gravitational influence on “normal” matter — is thought to make up five-sixths of all matter in the universe.

Astronomers began suspecting the existence of dark matter when they noticed the cosmos seemed to possess more mass than stars could account for.

For example, stars circle the center of the Milky Way so fast that they should overcome the gravitational pull of the galaxy’s core and zoom into the intergalactic void.

Most scientists think dark matter provides the gravity that helps hold these stars back.

Scientists have mostly ruled out all known ordinary materials as candidates for dark matter. The consensus so far is that this missing mass is made up of new species of particles that interact only very weakly with ordinary matter.

One potential clue about the nature of dark matte rhas to do with the fact that it’s five times more abundant than normal matter, researchers said.

This may seem a lot, and it is, but if dark and ordinary matter were generated in a completely independent way, then this number is puzzling,” said study co-author Pavlos Vranas, a particle physicist at Lawrence Livermore National Laboratory in Livermore, California.

Instead of five, it could have been a million or a billion. Why five?

The researchers suggest a possible solution to this puzzle: Dark matter particles once interacted often with normal matter, even though they barely do so now.

The protons and neutrons making up atomic nuclei are themselves each made up of a trio of particles known as quarks.

The researchers suggest dark matter is also made of a composite “stealth” particle, which is composed of a quartet of component particles and is difficult to detect.

The scientists’ supercomputer simulations suggest these composite particles may have masses ranging up to more than 200 billion electron-volts, which is about 213 times a proton’s mass.

Quarks each possess fractional electrical charges of positive or negative one-third or two-thirds. In protons, these add up to a positive charge, while in neutrons, the result is a neutral charge.

Quarks are confined within protons and neutrons by the so-called “strong interaction.

The researchers suggest that the component particles making up stealth dark matter particles each have a fractional charge of positive or negative one-half, held together by a “dark form” of the strong interaction.

Stealth dark matter particles themselves would only have a neutral charge, leading them to interact very weakly at best with ordinary matter, light, electric fields and magnetic fields.

The researchers suggest that at the extremely high temperatures seen in the newborn universe, the electrically charged components of stealth dark matter particles could have interacted with ordinary matter.

However, once the universe cooled, a new, powerful and as yet unknown force might have bound these component particles together tightly to form electrically neutral composites.

Stealth dark matter particles should be stable — not decaying over eons, if at all, much like protons.

However, the researchers suggest the components making up stealth dark matter particles can form different unstable composites that decay shortly after their creation.

These unstable particles might have masses of about 100 billion electron-volts or more, and could be created by particle accelerators such as the Large Hadron Collider (LHC) beneath the France-Switzerland border. They could also have an electric charge and be visible to particle detectors, Vranas said.

Experiments at the LHC, or sensors designed to spot rare instances of dark matter colliding with ordinary matter, “may soon find evidence of, or rule out, this new stealth dark matter theory,” Vranas said in a statement.

If stealth dark matter exists, future research can investigate whether there are any effects it might have on the cosmos.

The scientists, the Lattice Strong Dynamics Collaboration, will detail their findings in an upcoming issue of the journal Physical Review Letters.

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Pass it on: New Scientist