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It’s Been 32 Years Since We Last Explored Uranus

The blue-green crescent of Uranus imaged by a departing Voyager 2 on January 25, 1986 (NASA)

The blue-green crescent of Uranus imaged by a departing Voyager 2 on January 25, 1986 (NASA)

Voyager 2 may have been the second of NASA’s famous twin exploration spacecraft but it actually launched first, on August 20, 1977. Eight and a half years later it became the first (and, to date, last) spacecraft to visit Uranus, at 31,500 miles across the third largest planet in the Solar System. Voyager 2 made its closest pass by Uranus 32 years ago, giving us our best views ever of the enormous ice giant planet and its moons.

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Eppur Si Muove: Galileo’s Big Night

Jupiter and its four largest “Galilean” moons photographed on April 16, 2016. © Jason Major

On this night in 1610 the Pisan astronomer Galileo Galilei looked up at a bright Jupiter at opposition through his handmade telescope and noted three little “stars” next to it, piquing his natural scientific curiosity. Further observations over the next few nights showed that the planet wasn’t moving relative to the little “stars” as it would have if they were indeed background stars. In fact the smaller objects (of which he soon saw four) were moving along with Jupiter, each in its own little path. He realized that the little objects weren’t stars at all but rather moons orbiting the giant planet—and, most importantly, not the Earth. This revelation helped change our entire view of the Solar System… and caused no end of trouble for Galileo as the Church didn’t appreciate a restructuring of their conveniently Earth-centered Universe. But it also opened the door for later discoveries of many more moons around other planets.

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Answers to 8 Questions About the August 2017 Solar Eclipse

It’s August and one of the most highly-anticipated astronomical events of the 21st century is nearly upon us: the August 21 solar eclipse, which will be visible as a total eclipse literally across the entire United States…but that doesn’t mean everywhere in the United States. Totality will pass across the U.S. in a narrow band about 60 miles wide starting along the northern coast of Oregon at 10:18 a.m. local time (PDT) and ending along the coast of South Carolina at 2:48 p.m. EDT. But that’s just totality—the full eclipse event will actually begin much earlier than that and end later, and its visibility won’t be limited to only that path. And while it’ll be happening overhead in the daytime sky you’ll need the right equipment to view it safely, whether you’re in totality or not.

Wait, you say, what’s the difference between totality and…not totality? And how is it caused? And why is this a big deal at all? If you’re wondering those things (and perhaps others) then this post is just for you. Below are answers to some common—and certainly not dumb—questions about the solar eclipse, brought to you by yours truly (with a little help from NASA and other eclipse specialists.)

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Uranus Lights Up for Hubble

HST images of Uranus’ aurorae and rings combined with Voyager 2 images of the planet itself. (NASA)

Those white areas aren’t clouds; they’re aurorae—”northern lights”—around the poles of Uranus, captured by the Hubble Space Telescope in 2012 and 2014. (The image of Uranus itself was acquired by the Voyager 2 spacecraft in January 1986.)

“The auroras on Jupiter and Saturn are well-studied, but not much is known about the auroras of the giant ice planet Uranus. In 2011, the NASA/ESA Hubble Space Telescope became the first Earth-based telescope to snap an image of the auroras on Uranus. In 2012 and 2014 a team led by an astronomer from Paris Observatory took a second look at the auroras using the ultraviolet capabilities of the Space Telescope Imaging Spectrograph (STIS) installed on Hubble.”

Aurorae on Uranus are driven by the same process that creates them around Earth’s polar regions: charged particles from the Sun get caught in the planet’s magnetic field and are focused toward the poles, where they make ions in the upper atmosphere release energy—in these observations in ultraviolet wavelengths. Also, since Uranus orbits the Sun “tilted sideways” its polar regions are near the plane of its orbit.

Read the rest of this article from NASA here: Hubble Spots Auroras on Uranus

Here’s Hubble’s Newest Knockout Portrait of Jupiter

Jupiter imaged by the Hubble Space Telescope on April 3, 2017. Credit: NASA, ESA, and A. Simon (GSFC)

On April 3, 2017, as Jupiter made its nearest approach to Earth in a year, NASA’s Hubble Space Telescope viewed the solar system’s largest planet in all of its up-close glory. At a distance of 415 million miles (668 million km) from Earth, Jupiter offered spectacular views of its colorful, roiling atmosphere, the legendary Great Red Spot, and its smaller companion at farther southern latitudes dubbed “Red Spot Jr.” Taken with Hubble’s Wide Field Camera 3, the image resolves details in Jupiter’s atmosphere as small as about 80 miles (129 km) across.

Read the full article on NASA’s Hubble site here, and check out a version I made with enhanced contrast and sharpness to bring out some details in Jupiter’s clouds below:

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