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As seen on #Cosmos: We now know that comets are leftovers from the dawn of our solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. They have been referred to as "dirty snowballs." They may yield important clues about the formation of our solar system. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system. As theorized by astronomer Gerard Kuiper in 1951, a disc-like belt of icy bodies exists beyond Neptune, where a population of dark comets orbits the sun in the realm of Pluto. These icy objects, occasionally pushed by gravity into orbits bringing them closer to the sun, become the so-called short-period comets. Taking less than 200 years to orbit the sun, in many cases their appearance is predictable because they have passed by before. Less predictable are long-period comets, many of which arrive from a region called the Oort Cloud about 100,000 astronomical units (that is,100,000 times the distance between Earth and the Sun) from the Sun. These Oort Cloud comets can take as long as 30 million years to complete one trip around the Sun. Each comet has a tiny frozen part, called a nucleus, often no larger than a few kilometers across. The nucleus contains icy chunks, frozen gases with bits of embedded dust. A comet warms up as it nears the Sun and develops an atmosphere, or coma. The sun's heat causes the comet's ices to change to gases so the coma gets larger. The coma may extend hundreds of thousands of kilometers. The pressure of sunlight and high-speed solar particles (solar wind) can blow the coma dust and gas away from the Sun, sometimes forming a long, bright tail. Comets actually have two tails - a dust tail and an ion (gas) tail. This image of Comet C/2001 Q4 (NEAT) was taken at the WIYN 0.9-meter telescope at Kitt Peak National Observatory near Tucson, Ariz. on 7 May 2004. Credit: NSF #comets #solarsystem #universe #galaxy #space; -
As seen on #Cosmos: A spherical shell of icy bodies surrounding the solar system, now named the Oort Cloud, occupies space at a distance between 5,000 and 100,000 astronomical units. (One astronomical unit, or AU, is the mean distance of Earth from the sun: about 150 million km or 93 million miles.) The outer extent of the Oort Cloud is believed to be in the region of space where the sun's gravitational influence is weaker than the influence of nearby stars. The Oort Cloud probably contains 0.1 to 2 trillion icy bodies in solar orbit. Occasionally, giant molecular clouds, stars passing nearby, or tidal interactions with the Milky Way's disc disturb the orbits of some of these bodies in the outer region of the Oort Cloud, causing the object to fall into the inner solar system as a so-called long-period comet. These comets have very large, eccentric orbits and take thousands of years to circle the sun. In recorded history, they are observed in the inner solar system only once. This artist's concept puts solar system distances in perspective. The scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the sun to the Earth, which is about 93 million miles or 150 million kilometers. Neptune, the most distant planet from the sun, is about 30 AU. Informally, the term "solar system" is often used to mean the space out to the last planet. Scientific consensus, however, says the solar system goes out to the Oort Cloud, the source of the comets that swing by our sun on long time scales. Beyond the outer edge of the Oort Cloud, the gravity of other stars begins to dominate that of the sun. NASA's Voyager 1, humankind's most distant spacecraft, is around 125 AU. Image credit: NASA/JPL-Caltech #nasa #space #universe #oortcloud #solarsystem #planets; -
Astronaut Rick Mastracchio shared this wide angle shot out the cupola window on the International Space Station while orbiting "somewhere over Africa" earlier today. Aboard the orbiting complex Friday, Koichi Wakata, Mastracchio and Mikhail Tyurin tackled a range of scientific experiments and performed some routine maintenance and cleaning to get the station shipshape for the arrival of their three new crewmates on Tuesday. The Soyuz carrying NASA astronaut Steve Swanson and Russian cosmonauts Alexander Skvortsov and Oleg Artemyev is scheduled to lift off from Baikonur at 5:17 p.m. EDT Tuesday (3:17 a.m. Wednesday, Kazakh time) and dock to the Poisk mini-research module at 11:04 p.m. NASA Television will provide live coverage of all the events, including the hatch opening planned for 12:45 a.m. Wednesday. Image credit: NASA #nasa #space #iss #spacestation #africa #earthpix #earth #onorbit; -
It's World Water Day! Did you know that less than 3% of Earth's water is freshwater. This includes the Great Lakes, which are visible in this oblique 35mm image exposed from a space shuttle mission. Lake Ontario is in the foreground. The Niagara Falls area and Lake Erie are illuminated by sunglint just below center frame. Detroit is visible just above center. Photo credit: NASA #greatlakes #nasa #space #niagarafalls #lakeerie #lakeontario #detroit #earth #earthrightnow @worldwaterday; -
It's World Water Day! While our home planet is about 71 percent water, only 3 percent of that is available as fresh water. And many people do not have access to safe and clean water sources. On a water planet like Earth, "following the water" is a massive undertaking but one that is essential to predicting the future of our climate and the availability of water resources around the globe. Viewed from space, the most striking feature of our planet is the water. In both liquid and frozen form, it covers 75% of the Earth's surface. It fills the sky with clouds. Water is practically everywhere on Earth, from inside the rocky crust to inside our cells. Image Credit: NASA/MODIS #space #water #clouds #nasa #worldwaterday #earth #earthrightnow;
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After two successful surveys from Thule Air Base, IceBridge packed up and headed to Fairbanks, Alaska, for a temporary deployment there. For the past few years IceBridge has flown surveys from Fairbanks to study sea ice in the Beaufort and Chukchi seas north of Alaska. These flights allow researchers to study a region of growing interest and collect data across the entire Arctic Basin on the way between Greenland and Alaska. IceBridge has a couple more surveys to fly from Fairbanks before finishing up its week-long Alaska deployment. Once finished, the P-3 will head back across the Arctic Basin to continue collecting sea ice data out of Thule Air Base in Greenland. IceBridge, a six-year NASA mission, is the largest airborne survey of Earth's polar ice ever flown. This image is of mountains in Alaska's Brooks Range seen during the IceBridge survey flight from Thule, Greenland, to Fairbanks, Alaska. Credit: NASA / Michael Studinger #earthrightnow #ice #climatechange #climate #nasa #earth #science #icebridge #alaska; -
This new Hubble image is centered on NGC 5793, a spiral galaxy over 150 million light-years away in the constellation of Libra. This galaxy has two particularly striking features: a beautiful dust lane and an intensely bright center - much brighter than that of our own galaxy, or indeed those of most spiral galaxies we observe. It's a is a Seyfert galaxy. These galaxies have incredibly luminous centers that are thought to be caused by hungry supermassive black holes - black holes that can be billions of times the size of the sun - that pull in and devour gas and dust from their surroundings. Credit: NASA, ESA, and E. Perlman (Florida Institute of Technology) #nasa #hubble #hst #space #astronomy #galaxy #science; -
The International Space Station's Expedition 39 crew members spent Thursday conducting science experiments and performing routine maintenance to get their orbital home in shape for the arrival of three new crewmates. NASA astronaut Steve Swanson and Russian cosmonauts Alexander Skvortsov and Oleg Artemyev are scheduled to lift off from Baikonur at 5:17 p.m. EDT Tuesday and dock at 11:04 p.m. In this photo, Japan Aerospace Exploration Agency astronaut Koichi Wakata uses a still camera to photograph the topography of a point on Earth from a window in the cupola of the space station. Image Credit: NASA #iss #nasa #space #astronauts #exp39 #research #science #jaxa #spacestation; -
Happy Spring! This full-disk image from NOAA’s GOES-13 satellite was captured at 11:45 UTC (7:45 a.m. EDT) and shows the Americas on March 20, 2014. This date marks the start of astronomical spring in the northern hemisphere. GOES is the Geostationary Operational Environmental Satellites satellite. Geostationary describes an orbit in which a satellite is always in the same position with respect to the rotating Earth. This allows GOES to hover continuously over one position on the Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms, and hurricanes. Image Credit: NASA/NOAA GOES Project #nasa#earth #space #goes #irl #today #planets #solarsystem #home #spring #happyspring #firstdayofspring; -
A powerful storm passed over New Zealand’s South Island in March 2014 and brought gale-force winds, torrential rains, and flooding to the city of Christchurch. A total of 74 millimeters (3 inches) of rain fell on March 4-5, according to MetService, New Zealand’s national meteorological service. More than 100 homes flooded and more than 4,000 lost power around the country’s third most populous city. Skies had cleared enough by March 6, 2014, for the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite to acquire this image showing the aftermath. Coastal communities are becoming increasingly vulnerable to the risk of damage and danger from flooding. NASA and NOAA are together launching a new opportunity for citizens to work with us on the very important topic of coastal flooding. This coastal flooding challenge is part of NASA’s third International Space Apps Challenge - a two-day global mass collaboration event on April 12-13, 2014. During these two days, citizens around the world are invited to engage directly with NASA to develop awe-inspiring software, hardware, and data visualizations. Last year’s event involved more than 9,000 global participants in 83 locations. This year will introduce more than 60 robust challenges clustered in five themes: asteroids, Earth watch, human spaceflight, robotics, and space technology. The Coastal Inundation In Your Community challenge is one of four climate-related challenges using data provided by NASA, NOAA and EPA. Image Credit: NASA - Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response Team at NASA GSFC;
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Give Me Some 'Space'! If two is company and three is a crowd, what is four - especially when you are living and working in close quarters and under stress for several days? That is what our Flight Analogs Project set to find out when it sent four crew members on a simulated mission to the Geographos asteroid on Feb. 27. This initiated the first of many missions that will take place inside the Human Exploration Research Analog (HERA) located at NASA's Johnson Space Center in Houston. Investigators conducted behavioral health, human factors and countermeasures experiments on the four crew members who were crowded into the 148-cubic-meter HERA for seven days to determine how confinement and isolation impacts cohabitation, teamwork, team cohesion, mood, performance and overall well-being. Image Credit: NASA #nasa #asteroid #science #nasa humanfactors #exploration #space #health; -
A New Gully Channel in Terra Sirenum, Mars! This pair of before (left) and after (right) images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter documents the formation of a substantial new channel on a Martian slope between Nov. 5, 2010, and May 25, 2013. Gully or ravine landforms are commonly found in the mid-latitudes on Mars, particularly in the southern highlands. These features typically have an alcove at the upper end, feeding into a channel and an apron of debris that has been carried from above. Researchers using HiRISE have discovered many examples of gully activity likely driven by seasonal carbon-dioxide frost (dry ice). The changes visible by comparing the 2010 and 2013 observations at this site formed when material flowing down from the alcove broke out of an older route, eroded a new channel and formed a deposit on the apron. Although this pair of observations does not pin down the season of the event, locations HiRISE has imaged more often demonstrate that this sort of event generally occurs in winter, when liquid water is very unlikely. Despite their resemblance to water-formed ravines on Earth, carbon dioxide may play a key role in the formation of many Martian gullies. Image credit: NASA/JPL-Caltech/Univ. of Arizona #mars #hirise #mro #planets #gully #water #science; -
Jupiter's Great Red Spot! At about 89,000 miles in diameter, Jupiter could swallow 1,000 Earths. It is the largest planet in the solar system and perhaps the most majestic. Vibrant bands of clouds carried by winds that can exceed 400 mph continuously circle the planet's atmosphere. Such winds sustain spinning anticyclones like the Great Red Spot -- a raging storm three and a half times the size of Earth located in Jupiter’s southern hemisphere. In January and February 1979, NASA's Voyager 1 spacecraft zoomed toward Jupiter, capturing hundreds of images during its approach, including this close-up of swirling clouds around Jupiter's Great Red Spot. This image was assembled from three black and white negatives. The observations revealed many unique features of the planet that are still being explored to this day. Credit: NASA's Goddard Space Flight Center. #nasa #voyager #jupiter @planet @space @solarsystem #science #storm; -
The sun unleashed a M-9.3 flare, just short of an X class (the largest) from an active region right at the sun's edge (March 12-13, 2014). The bright flash is the tell-tale sign of a flare. The brightness of the flare causes very bright saturation and blooming above and below the flare region on the CCD detector and caused extended diffraction patterns to spread out across the SDO imager. Images were taken in extreme ultraviolet light, showing ionized iron at 10 million degrees. Credit: Solar Dynamics Observatory/NASA #nasa #sun #solar #flare #space #science; -
Scientists, using cameras aboard NASA's Lunar Reconnaissance Orbiter (LRO), have created the largest high resolution mosaic of our moon’s north polar region. The six-and-a-half feet (two-meters)-per-pixel images cover an area equal to more than one-quarter of the United States. The images making up the mosaic were taken by the two LRO Narrow Angle Cameras, which are part of the instrument suite known as the Lunar Reconnaissance Orbiter Camera (LROC). The cameras can record a tremendous dynamic range of lit and shadowed areas. Web viewers can zoom in and out, and pan around an area. Constructed from 10,581 pictures, the mosaic provides enough detail to see textures and subtle shading of the lunar terrain. Consistent lighting throughout the images makes it easy to compare different regions. Image Credit: NASA/GSFC/Arizona State University #moon #mosaic #nasa #space #lro #lunar #exploration #science;
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