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New Evidence Points to a Giant Ninth Planet in Our Solar System

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In a paper published today in the Astronomical Journal, astronomers Michael E. Brown and Konstantin Batygin report that there is new evidence that suggests the presence of a giant icy planet at the edge of our solar system that is 10 times the mass of Earth. 

The new planet, dubbed "Planet Nine," hasn't been observed directly, but The Washington Post writes that Brown and Batygin have "inferred its existence from the motion of recently discovered dwarf planets and other small objects in the outer solar system." The orbits of the small planets appear to be affected by the gravity of the larger Planet Nine, which is believed to have an "estimated mass would make it about two to four times the diameter of the Earth, distinguishing it as the fifth-largest planet after Jupiter, Saturn, Uranus, and Neptune," the paper notes. Scientists are currently searching for the new planet, but with an estimated distance 20 times farther than Neptune, it may not reflect enough sunlight to be seen by even the most powerful telescopes. 

Michael E. Brown, the "Pluto Killer" astronomer whose discovery of the dwarf planet Eris led to the reclassification of Pluto by the International Astronomical Union, spoke with the Post about Planet Nine and the possibility that it could one day take the former ninth planet's place. Brown explains that scientists cannot yet say that Planet Nine was "discovered" because "discovery means it’s been seen. Someone has seen it, has seen it move, has seen the orbit. We think we know the orbit, but we don't know where on that orbit the planet is, and we haven't seen it yet. This paper we published is like handing everyone a treasure map."

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Watch Apollo 11 Launch
Vice President Spiro Agnew and former President Lyndon Johnson view the liftoff of Apollo 11
Vice President Spiro Agnew and former President Lyndon Johnson view the liftoff of Apollo 11
NASA, Getty Images

Apollo 11 launched on July 16, 1969, on its way to the moon. In the video below, Mark Gray shows slow-motion footage of the launch (a Saturn V rocket) and explains in glorious detail what's going on from a technical perspective—the launch is very complex, and lots of stuff has to happen just right in order to get a safe launch. The video is mesmerizing, the narration is informative. Prepare to geek out about rockets! (Did you know the hold-down arms actually catch on fire after the rocket lifts off?)

Apollo 11 Saturn V Launch (HD) Camera E-8 from Spacecraft Films on Vimeo.

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Astronomers Discover 12 New Moons Around Jupiter
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As the largest planet with the largest moon in our solar system, Jupiter is a body of record-setting proportions. The fifth planet from the Sun also boasts the most moons—and scientists just raised the count to 79.

A team of astronomers led by Scott S. Sheppard of the Carnegie Institute for Science confirmed the existence of 12 additional moons of Jupiter, 11 of which are “normal” outer moons, according to a statement from the institute. The outlier is being called an “oddball” for its bizarre orbit and diminutive size, which is about six-tenths of a mile in diameter.

The moons were first observed in the spring of 2017 while scientists looked for theoretical planet beyond Pluto, but several additional observations were needed to confirm that the celestial bodies were in fact orbiting around Jupiter. That process took a year.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” Sheppard said in a statement.

Nine of the "normal" moons take about two years to orbit Jupiter in retrograde, or counter to the direction in which Jupiter spins. Scientists believe these moons are what’s left of three larger parent bodies that splintered in collisions with asteroids, comets, or other objects. The two other "normal" moons orbit in the prograde (same direction as Jupiter) and take less than a year to travel around the planet. They’re also thought to be chunks of a once-larger moon.

The oddball, on the other hand, is “more distant and more inclined” than the prograde moons. Although it orbits in prograde, it crosses the orbits of the retrograde moons, which could lead to some head-on collisions. The mass is believed to be Jupiter’s smallest moon, and scientists have suggested naming it Valetudo after the Roman goddess of health and hygiene, who happens to be the great-granddaughter of the god Jupiter.

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