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What’s Up For August 2018?

The summer Perseids are here! 

The Perseid meteor shower is the best of the year! It peaks on a Moonless summer night from 4 p.m. EST on August 12 until 4 a.m. EST on August 13.

Because the new Moon falls near the peak night, the days before and after the peak will also provide nice, dark skies. Your best window of observation is from a few hours after twilight until dawn, on the days surrounding the peak.

Unlike most meteor showers, which have a short peak of high meteor rates, the Perseids have a very broad peak, as Earth takes more than three weeks to plow through the wide trail of cometary dust from comet Swift-Tuttle.

The Perseids appear to radiate from the constellation Perseus, visible in the northern sky soon after sunset this time of year. Observers in mid-northern latitudes will have the best views.

You should be able to see some meteors from July 17 to August 24, with the rates increasing during the weeks before August 12 and decreasing after August 13.

Observers should be able to see between 60 and 70 per hour at the peak. Remember, you don’t have to look directly at the constellation to see them. You can look anywhere you want to-even directly overhead.

Meteor showers like the Perseids are caused by streams of meteoroids hitting Earth’s atmosphere. The particles were once part of their parent comet-or, in some cases, from an asteroid.

The parade of planets Venus, Jupiter, Saturn and Mars–and the Milky Way continue to grace the evening sky, keeping you and the mosquitoes company while you hunt for meteors.

Watch the full What’s Up for August Video: 

There are so many sights to see in the sky. To stay informed, subscribe to our What’s Up video series on Facebook.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

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Frozen: Ice on Earth and Well Beyond

Icy Hearts: A heart-shaped calving front of a glacier in Greenland (left) and Pluto’s frozen plains (right). Credits: NASA/Maria-Jose Viñas and NASA/APL/SwRI

From deep below the soil at Earth’s polar regions to Pluto’s frozen heart, ice exists all over the solar system…and beyond. From right here on our home planet to moons and planets millions of miles away, we’re exploring ice and watching how it changes. Here’s 10 things to know:

1. Earth’s Changing Ice Sheets

An Antarctic ice sheet. Credit: NASA

Ice sheets are massive expanses of ice that stay frozen from year to year and cover more than 6 million square miles. On Earth, ice sheets extend across most of Greenland and Antarctica. These two ice sheets contain more than 99 percent of the planet’s freshwater ice. However, our ice sheets are sensitive to the changing climate.

Data from our GRACE satellites show that the land ice sheets in both Antarctica and Greenland have been losing mass since at least 2002, and the speed at which they’re losing mass is accelerating.

2. Sea Ice at Earth’s Poles

Earth’s polar oceans are covered by stretches of ice that freezes and melts with the seasons and moves with the wind and ocean currents. During the autumn and winter, the sea ice grows until it reaches an annual maximum extent, and then melts back to an annual minimum at the end of summer. Sea ice plays a crucial role in regulating climate – it’s much more reflective than the dark ocean water, reflecting up to 70 percent of sunlight back into space; in contrast, the ocean reflects only about 7 percent of the sunlight that reaches it. Sea ice also acts like an insulating blanket on top of the polar oceans, keeping the polar wintertime oceans warm and the atmosphere cool.

Some Arctic sea ice has survived multiple years of summer melt, but our research indicates there’s less and less of this older ice each year. The maximum and minimum extents are shrinking, too. Summertime sea ice in the Arctic Ocean now routinely covers about 30-40 percent less area than it did in the late 1970s, when near-continuous satellite observations began. These changes in sea ice conditions enhance the rate of warming in the Arctic, already in progress as more sunlight is absorbed by the ocean and more heat is put into the atmosphere from the ocean, all of which may ultimately affect global weather patterns.

3. Snow Cover on Earth

Snow extends the cryosphere from the poles and into more temperate regions.

Snow and ice cover most of Earth’s polar regions throughout the year, but the coverage at lower latitudes depends on the season and elevation. High-elevation landscapes such as the Tibetan Plateau and the Andes and Rocky Mountains maintain some snow cover almost year-round. In the Northern Hemisphere, snow cover is more variable and extensive than in the Southern Hemisphere.

Snow cover the most reflective surface on Earth and works like sea ice to help cool our climate. As it melts with the seasons, it provides drinking water to communities around the planet.

4. Permafrost on Earth

Tundra polygons on Alaska’s North Slope. As permafrost thaws, this area is likely to be a source of atmospheric carbon before 2100. Credit: NASA/JPL-Caltech/Charles Miller

Permafrost is soil that stays frozen solid for at least two years in a row. It occurs in the Arctic, Antarctic and high in the mountains, even in some tropical latitudes. The Arctic’s frozen layer of soil can extend more than 200 feet below the surface. It acts like cold storage for dead organic matter – plants and animals.

In parts of the Arctic, permafrost is thawing, which makes the ground wobbly and unstable and can also release those organic materials from their icy storage. As the permafrost thaws, tiny microbes in the soil wake back up and begin digesting these newly accessible organic materials, releasing carbon dioxide and methane, two greenhouse gases, into the atmosphere.

Two campaigns, CARVE and ABoVE, study Arctic permafrost and its potential effects on the climate as it thaws.

5. Glaciers on the Move

Did you know glaciers are constantly moving? The masses of ice act like slow-motion rivers, flowing under their own weight. Glaciers are formed by falling snow that accumulates over time and the slow, steady creep of flowing ice. About 10 percent of land area on Earth is covered with glacial ice, in Greenland, Antarctica and high in mountain ranges; glaciers store much of the world’s freshwater.

Our satellites and airplanes have a bird’s eye view of these glaciers and have watched the ice thin and their flows accelerate, dumping more freshwater ice into the ocean, raising sea level.

6. Pluto’s Icy Heart

The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo: numerous, isolated hills that may be fragments of water ice from Pluto’s surrounding uplands. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Pluto’s most famous feature – that heart! – is stone cold. First spotted by our New Horizons spacecraft in 2015, the heart’s western lobe, officially named Sputnik Planitia, is a deep basin containing three kinds of ices – frozen nitrogen, methane and carbon monoxide.

Models of Pluto’s temperatures show that, due the dwarf planet’s extreme tilt (119 degrees compared to Earth’s 23 degrees), over the course of its 248-year orbit, the latitudes near 30 degrees north and south are the coldest places – far colder than the poles. Ice would have naturally formed around these latitudes, including at the center of Sputnik Planitia.

New Horizons also saw strange ice formations resembling giant knife blades. This “bladed terrain” contains structures as tall as skyscrapers and made almost entirely of methane ice, likely formed as erosion wore away their surfaces, leaving dramatic crests and sharp divides. Similar structures can be found in high-altitude snowfields along Earth’s equator, though on a very different scale.

7. Polar Ice on Mars

This image, combining data from two instruments aboard our Mars Global Surveyor, depicts an orbital view of the north polar region of Mars. Credit: NASA/JPL-Caltech/MSSS

Mars has bright polar caps of ice easily visible from telescopes on Earth. A seasonal cover of carbon dioxide ice and snow advances and retreats over the poles during the Martian year, much like snow cover on Earth.

This animation shows a side-by-side comparison of CO2 ice at the north (left) and south (right) Martian poles over the course of a typical year (two Earth years). This simulation isn’t based on photos; instead, the data used to create it came from two infrared instruments capable of studying the poles even when they’re in complete darkness. This data were collected by our Mars Reconnaissance Orbiter, and Mars Global Surveyor. Credit: NASA/JPL-Caltech

During summertime in the planet’s north, the remaining northern polar cap is all water ice; the southern cap is water ice as well, but remains covered by a relatively thin layer of carbon dioxide ice even in summertime.

Scientists using radar data from our Mars Reconnaissance Orbiter found a record of the most recent Martian ice age in the planet’s north polar ice cap. Research indicates a glacial period ended there about 400,000 years ago. Understanding seasonal ice behavior on Mars helps scientists refine models of the Red Planet’s past and future climate.

8. Ice Feeds a Ring of Saturn

Wispy fingers of bright, icy material reach tens of thousands of kilometers outward from Saturn’s moon Enceladus into the E ring, while the moon’s active south polar jets continue to fire away. Credit: NASA/JPL/Space Science Institute

Saturn’s rings and many of its moons are composed of mostly water ice – and one of its moons is actually creating a ring. Enceladus, an icy Saturnian moon, is covered in “tiger stripes.” These long cracks at Enceladus’ South Pole are venting its liquid ocean into space and creating a cloud of fine ice particles over the moon’s South Pole. Those particles, in turn, form Saturn’s E ring, which spans from about 75,000 miles (120,000 kilometers) to about 260,000 miles (420,000 kilometers) above Saturn’s equator. Our Cassini spacecraft discovered this venting process and took high-resolution images of the system.

Jets of icy particles burst from Saturn’s moon Enceladus in this brief movie sequence of four images taken on Nov. 27, 2005. Credit: NASA/JPL/Space Science Institute

9. Ice Rafts on Europa

View of a small region of the thin, disrupted, ice crust in the Conamara region of Jupiter’s moon Europa showing the interplay of surface color with ice structures. Credit: NASA/JPL/University of Arizona

The icy surface of Jupiter’s moon Europa is crisscrossed by long fractures. During its flybys of Europa, our Galileo spacecraft observed icy domes and ridges, as well as disrupted terrain including crustal plates that are thought to have broken apart and “rafted” into new positions. An ocean with an estimated depth of 40 to 100 miles (60 to 150 kilometers) is believed to lie below that 10- to 15-mile-thick (15 to 25 km) shell of ice.

The rafts, strange pits and domes suggest that Europa’s surface ice could be slowly turning over due to heat from below. Our Europa Clipper mission, targeted to launch in 2022, will conduct detailed reconnaissance of Europa to see whether the icy moon could harbor conditions suitable for life.

10. Crater Ice on Our Moon

The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right), detected by our Moon Mineralogy Mapper instrument. Credit: NASA

In the darkest and coldest parts of our Moon, scientists directly observed definitive evidence of water ice. These ice deposits are patchy and could be ancient. Most of the water ice lies inside the shadows of craters near the poles, where the warmest temperatures never reach above -250 degrees Fahrenheit. Because of the very small tilt of the Moon’s rotation axis, sunlight never reaches these regions.

A team of scientists used data from a our instrument on India’s Chandrayaan-1 spacecraft to identify specific signatures that definitively prove the water ice. The Moon Mineralogy Mapper not only picked up the reflective properties we’d expect from ice, but was able to directly measure the distinctive way its molecules absorb infrared light, so it can differentiate between liquid water or vapor and solid ice.

With enough ice sitting at the surface – within the top few millimeters – water would possibly be accessible as a resource for future expeditions to explore and even stay on the Moon, and potentially easier to access than the water detected beneath the Moon’s surface.

11. Bonus: Icy World Beyond Our Solar System!

With an estimated temperature of just 50K, OGLE-2005-BLG-390L b is the chilliest exoplanet yet discovered. Pictured here is an artist’s concept. Credit: NASA

OGLE-2005-BLG-390Lb, the icy exoplanet otherwise known as Hoth, orbits a star more than 20,000 light years away and close to the center of our Milky Way galaxy. It’s locked in the deepest of deep freezes, with a surface temperature estimated at minus 364 degrees Fahrenheit (minus 220 Celsius)!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

What's Up - December 2017

What’s Up For December? Geminid and Ursid meteor showers & winter constellations!

This month hosts the best meteor shower of the year and the brightest stars in familiar constellations.

The Geminds peak on the morning of the 14th, and are active from December 4th through the 17th. The peak lasts for a full 24 hours, meaning more worldwide meteor watchers will get to see this spectacle.

Expect to see  up to 120 meteors per hour between midnight and 4 a.m. but only from a dark sky. You’ll see fewer after moonrise at 3:30 a.m. local time.

In the southern hemisphere, you won’t see as many, perhaps 10-20 per hour, because the radiant never rises above the horizon.

Take a moment to enjoy the circle of constellations and their brightest stars around Gemini this month.

Find yellow Capella in the constellation Auriga. 

Next-going clockwise–at 1 o'clock find Taurus and bright reddish Aldebaran, plus the Pleiades. 

At two, familiar Orion, with red Betelguese, blue-white Rigel, and the three famous belt stars in-between the two.   

Next comes Leo, and its white lionhearted star, Regulus at 7 o'clock.

Another familiar constellation Ursa Major completes the view at 9 o'clock.

There’s a second meteor shower in December, the Ursids, radiating from Ursa Minor, the Little Dipper. If December 22nd  and the morning of December 23rd are clear where you are, have a look at the Little Dipper’s bowl, and you might see about ten meteors per hour. Watch the full What’s Up for December Video: 

There are so many sights to see in the sky. To stay informed, subscribe to our What’s Up video series on Facebook. Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.   

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