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A Dozen New Moons Found Orbiting Jupiter

Twelve new moons orbiting Jupiter have been found -- 11 'normal' outer moons, and one that they're calling an 'oddball.'

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Jupiter
Astronomers Discovers 12 New Moons Orbiting Around Jupiter. (VOA)

Astronomers are still finding moons at Jupiter, 400 years after Galileo used his spyglass to spot the first ones.

The latest discovery of a dozen small moons brings the total to 79, the most of any planet in our solar system.

Scientists were looking for objects on the fringes of the solar system last year when they pointed their telescopes close to Jupiter’s backyard, according to Scott Sheppard of the Carnegie Institute for Science in Washington. They saw a new group of objects moving around the giant gas planet but didn’t know whether they were moons or asteroids passing near the planet.

“There was no eureka moment,” said Sheppard, who led the team of astronomers. “It took a year to figure out what these objects were.”

They all turned out to be moons of Jupiter. The confirmation of 10 was announced Tuesday. Two were confirmed earlier.

The moons had not been spotted before because they are tiny. They are about one to two kilometers across, said astronomer Gareth Williams of the International Astronomical Union’s Minor Planet Center.

And he thinks Jupiter might have even more moons just as small waiting to be found.

“We just haven’t observed them enough,” said Williams, who helped confirm the moons’ orbits.

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12 New Moons Discovered Orbiting Jupiter. Pixabay

The team is calling one of the new moons an “oddball” because of its unusual orbit. Sheppard’s girlfriend came up with a name for it: Valetudo, the great-granddaughter of the Roman god Jupiter.

Valetudo is in Jupiter’s distant, outer swarm of moons that circles in the opposite direction of the planet’s rotation. Yet it’s orbiting in the same direction as the planet, against the swarm’s traffic.

“This moon is going down the highway the wrong way,” Sheppard said.

Scientists believe moons like Valetudo and its siblings appeared soon after Jupiter formed. The planet must have acted like a vacuum, sucking up all the material that was around it. Some of that debris was captured as moons.

“What astonishes me about these moons is that they’re the remnants of what the planet formed from,” he said.

Telescopes in Chile, Hawaii and Arizona were used for the latest discovery and confirmation.

Also Read-NASA Probes Unveils Stormy Environment of Jupiter’s moon

Galileo detected Jupiter’s four largest moons, Io, Europa, Ganymede and Callisto, in 1610. The latest count of 79 known moons includes eight that have not been seen for several years. Saturn is next with 61, followed by Uranus with 27 and Neptune with 14. Mars has two, Earth has one and Mercury and Venus have none. (VOA)

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Astronomers Measure Mass of Milky Way Galaxy

The Milky Way, the galaxy which contains Earth's solar system, is home to up to 400 billion stars and an estimated 100 billion planets.

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Milky way galaxy, scientists
The measurement includes all the stars and planets, dust and gas, as well as the four-million-solar-mass supermassive black hole at the center. Pixabay

Using data from NASA’s Hubble Space Telescope and the European Space Agency’s Gaia satellite, astronomers have come up with one of the most accurate measurements of mass of the Milky Way galaxy.

While previous research dating back several decades provided estimates for our galaxy’s mass, ranging between 500 billion to three trillion solar masses, according to the latest measurements, Milky Way weighs about 1.5 trillion solar masses (one solar mass is the mass of our Sun).

The measurement includes all the stars and planets, dust and gas, as well as the four-million-solar-mass supermassive black hole at the center.

“We want to know the mass of the Milky Way more accurately so that we can put it into a cosmological context and compare it to simulations of galaxies in the evolving universe,” said Roeland van der Marel of the Space Telescope Science Institute (STScI) in Baltimore, Maryland.

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The more massive a galaxy, the faster its globular clusters move under the pull of gravity, according to a forthcoming paper in The Astrophysical Journal. Pixabay

To weigh the galaxy, the team augmented Gaia measurements for 34 globular clusters out to 65,000 light-years, with Hubble measurements of 12 clusters out to 130,000 light-years that were obtained from images taken over a 10-year period.

They also measured the three-dimensional movement of globular star clusters – isolated spherical islands each containing hundreds of thousands of stars each that orbit the center of our galaxy.

The more massive a galaxy, the faster its globular clusters move under the pull of gravity, according to a forthcoming paper in The Astrophysical Journal.

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The new mass estimate puts our galaxy on the beefier side, compared to other galaxies in the universe. The lightest galaxies are around a billion solar masses, while the heaviest are 30 trillion, or 30,000 times more massive.

The Milky Way, the galaxy which contains Earth’s solar system, is home to up to 400 billion stars and an estimated 100 billion planets. (IANS)