These Stunning 3D Images Reveal How a Massive Greenland Glacier Has Changed


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These Stunning 3D Images Reveal How a Massive Greenland Glacier Has Changed

Watching a glacier

Credit: Jefferson Beck/NASA Goddard

Gorgeous Crater Lake Stuns in This Photo from Space


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Gorgeous Crater Lake Stuns in This Photo from Space

Crater Lake, the deepest lake in the United States, was formed after eruption and collapse of Mount Mazama 7,700 years ago.

Credit: NASA Earth Observatory

Southern Oregon’s idyllic Crater Lake — snow ringed and shade dappled — belies its violent past.

This image, taken by an astronaut aboard the International Space Station, was released July 31 by NASA’s Earth Observatory. Crater Lake’s midnight-blue waters are mottled only by the shadows cast by clouds and Wizard Island (at right of the frame), stippled in snow.

The caldera — the volcanic bowl of the lake — was formed 7,700 years ago after the volcano Mount Mazama erupted, spewing pumice and ash skyward, reaching heights of up to 30 miles (50 kilometers). The excess of magma then caused the volcano to collapse. Rain and snow filled the caldera, outpacing the lava that continued to flow from further smaller eruptions, until the lake was formed, according to the United States Geological Survey. [The 10 Biggest Volcanic Eruptions in History]

The Wizard Island peak —which science teacher Tom McDonough observed in one of the Crater Lake Institute’s Nature Notes From Crater Lake “somehow seems fitting to have a winged dinosaur fly in circles around the cone” —is one of the only remnants of the volcano’s fiery past that can be seen above the surface. Further clues, however, remain along the lake floor. In 2000, scientists conducted a bathymetry survey, a study of the topography of the lake bottom, which revealed that the lake’s depths contain a lava dome, cone and traces of a landslide.

Other crater lakes have similarly tumultuous histories. The supervolcano that formed the vast Indonesian Lake Toba 75,000 years ago spewed ash more than 4,350 miles (7,000 km), about the distance between Chicago and Hawaii. More recently, the 1991 eruption of Mount Pinatubo in the Philippines not only unleashed a 100-mile-wide (160 km) cloud of ash, but also created hot ash avalanches and enormous mudflows. This powerful eruption created the caldera that now contains serene Lake Pinatubo.

Original article on Live Science.

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Do Other Planets Have Solar Eclipses?


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Do Other Planets Have Solar Eclipses?

The Mars rover Curiosity took these images of an annular, or ring, eclipse as Mars’ largest moon, Phobos, passed directly in front of the sun on Aug. 20, 2013. The photos were taken 3 seconds apart.

Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M University

As Earthlings, we have the privilege of ooohing and aaahing at total solar eclipses, those dazzling celestial events in which the moon blocks the sun’s light from hitting our planet. But is Earth the only world in our solar system that experiences this spectacular phenomenon?

The answer is no. Total solar eclipses can happen on other planets too, as long as they have moons that are big enough to cover the sun’s disk from the planet’s perspective and orbit the planet on the same plane as the sun, astronomers told Live Science.

A total solar eclipse occurs when a planet, its moon and the sun are aligned along the same plane, and a substantially sized moon passes between the planet and its sun, totally blocking the sun’s light from reaching the planet.

“To get a solar eclipse, the first thing you need is a moon,” said Christa Van Laerhoven, a postdoctoral fellow of astronomy at the University of British Columbia in Canada. “This immediately rules out solar eclipses on Mercury or Venus” — two planets without moons, she said. [What Would Earth Be Like with Two Suns?]

Mars has two moons — Phobos and Deimos — but both are too small to create total solar eclipses that would be visible from the Red Planet. Rather, these moons can make partial eclipses for any potential life-form (or Mars rover) watching from the ground, Van Laerhoven said.

“The view from those little moons is more interesting: They see Mars eclipsing the sun very frequently, and during some seasons, it happens every day,” astronomer Matija Cuk wrote on the Cornell University blog “Ask an Astronomer.”

The gas giants — Jupiter, Saturn, Uranus and Neptune — can all have total solar eclipses, as they have large moons and the sun appears small to them, Cuk said. But because these planets are made of gas, it would be impossible to stand on them and see such solar eclipses, he said.

However, if you had a special spaceship that could hover near the swirling gas giants, you could very well glimpse a solar eclipse. Jupiter has up to 67 moons, including Ganymede, the largest moon in the solar system. Because Jupiter’s moons orbit on the same plane as the sun, the planet can have solar eclipses, Cuk and Van Laerhoven said.

In fact, if you could land on one of Jupiter’s moons, you could see its other moons eclipse the sun, the astronomers said.

But what about dwarf planets, such as Pluto? “It seems likely that Charon [Pluto’s largest moon] produces total solar eclipses for Pluto,” Van Laerhoven said. But because the same side of Pluto and Charon always face each other, “only one side of both Pluto and Charon will ever experience eclipses,” Cuk wrote.

On Earth, the moon is almost perfectly suited to making eclipses. The moon is the right size — that is, it appears to be the same size or larger than the apparent size of the sun, as seen from Earth. “This means that when the moon passes in front of the sun, the photosphere [the sun’s luminous outer shell] gets covered, but the corona [the sun’s upper atmosphere] remains visible,” Van Laerhoven said. [Why Total Solar Eclipses Are Total Coincidences]

She noted that Earth’s moon is slowly moving farther away from our planet, so in the distant future, the moon’s apparent size will be too small to entirely cover the sun, at least from Earth’s perspective. This means that one day, the moon won’t be able to cause total solar eclipses but only annular eclipses, in which a “ring” of the sun’s disk is still visible, Van Laerhoven said. Experts speculate that Earth will experience its last total solar eclipse about 600 million years from now.

For now, however, the moon is in prime location to cause a total solar eclipse.

“The reason we don’t get solar eclipses every month is because the moon’s orbital plane is slightly misaligned from Earth’s orbital plane around the sun,” Van Laerhoven said. “If they are misaligned, that decreases your chances of having a solar eclipse. You only get it when things happen to be lined up.”

REMEMBER: Looking directly at the sun, even when it is partially covered by the moon, can cause serious eye damage or blindness. NEVER look at a partial solar eclipse without proper eye protection. Our sister site Space.com has a complete guide for how to view an eclipse safely.

Original article on Live Science.