ScienceCasts: Evidence for Supernovas Near Earth

A NASA sounding rocket has confirmed that the solar system is inside an ancient supernova remnant. Life on Earth survived despite the nearby blasts.

 

NASA | Late Summer M5 Solar Flare

On Aug. 24, 2014, the sun emitted a mid-level solar flare, peaking at 8:16 a.m. EDT. NASA's Solar Dynamics Observatory and STEREO captured images of the flare, which erupted on the left side of the sun. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

To see how this event may affect Earth, please visit NOAA's Space Weather Prediction Center at http://spaceweather.gov, the U.S. government's official source for space weather forecasts, alerts, watches and warnings. This flare is classified as an M5 flare. M-class flares are ten times less powerful than the most intense flares, called X-class flares.

 

ScienceCasts: Sizing up an Exoplanet

Astronomers are not only discovering planets around distant suns, they are also starting to measure those worlds with astonishing precision. The diameter of a super-Earth named Kepler 93B is now known to within an accuracy of 148 miles.

 

NASA | Neutron Stars Rip Each Other Apart to Form Black Hole

This supercomputer simulation shows one of the most violent events in the universe: a pair of neutron stars colliding, merging and forming a black hole. A neutron star is the compressed core left behind when a star born with between eight and 30 times the sun's mass explodes as a supernova. Neutron stars pack about 1.5 times the mass of the sun — equivalent to about half a million Earths — into a ball just 12 miles (20 km) across.

As the simulation begins, we view an unequally matched pair of neutron stars weighing 1.4 and 1.7 solar masses. They are separated by only about 11 miles, slightly less distance than their own diameters. Redder colors show regions of progressively lower density.

As the stars spiral toward each other, intense tides begin to deform them, possibly cracking their crusts. Neutron stars possess incredible density, but their surfaces are comparatively thin, with densities about a million times greater than gold. Their interiors crush matter to a much greater degree densities rise by 100 million times in their centers. To begin to imagine such mind-boggling densities, consider that a cubic centimeter of neutron star matter outweighs Mount Everest.

By 7 milliseconds, tidal forces overwhelm and shatter the lesser star. Its superdense contents erupt into the system and curl a spiral arm of incredibly hot material. At 13 milliseconds, the more massive star has accumulated too much mass to support it against gravity and collapses, and a new black hole is born. The black hole's event horizon — its point of no return — is shown by the gray sphere. While most of the matter from both neutron stars will fall into the black hole, some of the less dense, faster moving matter manages to orbit around it, quickly forming a large and rapidly rotating torus. This torus extends for about 124 miles (200 km) and contains the equivalent of 1/5th the mass of our sun. The entire simulation covers only 20 milliseconds.

Scientists think neutron star mergers like this produce short gamma-ray bursts (GRBs). Short GRBs last less than two seconds yet unleash as much energy as all the stars in our galaxy produce over one year.

The rapidly fading afterglow of these explosions presents a challenge to astronomers. A key element in understanding GRBs is getting instruments on large ground-based telescopes to capture afterglows as soon as possible after the burst. The rapid notification and accurate positions provided by NASA's Swift mission creates a vibrant synergy with ground-based observatories that has led to dramatically improved understanding of GRBs, especially for short bursts.

 

ScienceCasts: A Sudden Multiplication of Planets

This week, NASA announced a breakthrough addition to the catalog of new planets. Researchers using Kepler have confirmed 715 new worlds, almost quadrupling the number of planets previously confirmed by the planet-hunting spacecraft. Some of the new worlds are similar in size to Earth and orbit in the habitable zone of their parent stars.

 

NASA | Jewel Box Sun

This video of the sun based on data from NASA's Solar Dynamics Observatory, or SDO, shows the wide range of wavelengths -- invisible to the naked eye -- that the telescope can view. SDO converts the wavelengths into an image humans can see, and the light is colorized into a rainbow of colors.

As the colors sweep around the sun in the movie, viewers should note how different the same area of the sun appears. This happens because each wavelength of light represents solar material at specific temperatures. Different wavelengths convey information about different components of the sun's surface and atmosphere, so scientists use them to paint a full picture of our constantly changing and varying star.

Yellow light of 5800 Angstroms, for example, generally emanates from material of about 10,000 degrees F (5700 degrees C), which represents the surface of the sun. Extreme ultraviolet light of 94 Angstroms, which is typically colorized in green in SDO images, comes from atoms that are about 11 million degrees F (6,300,000 degrees C) and is a good wavelength for looking at solar flares, which can reach such high temperatures. By examining pictures of the sun in a variety of wavelengths -- as is done not only by SDO, but also by NASA's Interface Region Imaging Spectrograph, NASA's Solar Terrestrial Relations Observatory and the European Space Agency/NASA Solar and Heliospheric Observatory -- scientists can track how particles and heat move through the sun's atmosphere.

 The 2.9 minute movie was created by NASA's Scientific Visualization Studio or SVS at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and is available at the SVS website: http://svs.gsfc.nasa.gov/goto?11385

 

ScienceCasts: Starting Fire in Water

Astronauts on the ISS are experimenting with a form of water that has a strange property: it can help start fire. This fundamental physics investigation could have down-to-Earth benefits such as clean-burning municipal waste disposal and improved saltwater purification.

 

NASA | Alien Atmospheres

Since the early 1990's, astronomers have known that extrasolar planets, or "exoplanets," orbit stars light-years beyond our own solar system. Although most exoplanets are too distant to be directly imaged, detailed studies have been made of their size, composition, and even atmospheric makeup - but how? By observing periodic variations in the parent star's brightness and color, astronomers can indirectly determine an exoplanet's distance from its star, its size, and its mass. But to truly understand an exoplanet astronomers must study its atmosphere, and they do so by splitting apart the parent star's light during a planetary transit.

 

NASA | Mars Atmosphere Loss: Neutral Processes

When you take a look at Mars, you probably wouldn't think that it looks like a nice place to live. It's dry, it's dusty, and there's practically no atmosphere. But some scientists think that Mars may have once looked like a much nicer place to live, with a thicker atmosphere, cloudy skies, and possibly even liquid water flowing over the surface. So how did Mars transform from a warm, wet world to a cold, barren desert? NASA's MAVEN spacecraft will give us a clearer idea of how Mars lost its atmosphere (and thus its water), and scientists think that several processes have had an impact. Scientists think that the collision of neutral hydrogen molecules may have helped to drive the Martian atmosphere into space over billions of years.

 

ScienceCasts: What Happened to Mars? A Planetary Mystery

Mars was once on track to become a thriving Earth-like planet, yet today it is an apparently lifeless wasteland. A NASA spacecraft named MAVEN will soon journey to Mars to find out what went wrong on the Red Planet.

 

NASA | Firefly Mission to Study Lightning

Somewhere on Earth, there's always a lightning flash. The globe experiences lightning some 50 times a second, yet the details of what initiates this common occurrence and what effects it has on the atmosphere - lightning may be linked to incredibly powerful and energetic bursts called terrestrial gamma ray flashes, or TGFs -- remains a mystery.

In mid-November, a football-sized mission called Firefly, which is funded by the National Science Foundation, will launch into space to study lightning and these gamma ray flashes from above.

The NSF CubeSat program represents a low cost access to space approach to performing high-quality, highly targeted science on a smaller budget than is typical of more comprehensive satellite projects, which have price tags starting at $100 million. The CubeSat Firefly, by focusing its science goals, will carry out its mission in a much smaller package and at a considerably lower cost.

 

NASA | Five Days of Flares and CMEs

This movie shows 23 of the 26 M- and X-class flares on the sun between 1800 UT Oct. 23 and 1500 UT Oct. 28, 2013, as captured by NASA's Solar Dynamics Observatory. It also shows the coronal mass ejections -- great clouds of solar material bursting off the sun into space -- during that time as captured by the ESA/NASA Solar and Heliospheric Observatory.

 

NASA | A Laser Scientist Answers 5 Questions About LVIS

With winter closing in, a new NASA airborne campaign launched October 31, 2013 in Greenland. For the first time, the Laser Vegetation Imaging Sensor, or LVIS, is flying about NASA's new C-130 aircraft to measure the island's ice following a summer's melt. This data will complement measurements the LVIS instrument has taken in previous springtime campaigns as a part of Operation IceBridge, a six-year multi-instrument survey over both Arctic and Antarctic ice.


 

ScienceCasts: The Sounds of Interstellar Space

As Voyager 1 recedes from the solar system, researchers are listening for "interstellar music" (a.k.a. plasma waves) to learn more about conditions outside the heliosphere.

 

NASA | Canyon of Fire on the Sun

A magnetic filament of solar material erupted on the sun in late September, breaking the quiet conditions in a spectacular fashion. The 200,000 mile long filament ripped through the sun's atmosphere, the corona, leaving behind what looks like a canyon of fire. The glowing canyon traces the channel where magnetic fields held the filament aloft before the explosion. Visualizers at NASA's Goddard Space Flight Center in Greenbelt, Md. combined two days of satellite data to create a short movie of this gigantic event on the sun.

 

ScienceCasts: The Effects of Space Weather on Aviation

Astronauts aren't the only ones who need to worry about solar flares. Ordinary air travelers can also be exposed to significant doses of radiation during solar storms. A new computer model developed by NASA aims to help protect the public by predicting space weather hazards to aviation.

 

ScienceCasts: Amateur Astonomers See Comet ISON Approaching the Sun

Comet ISON is still more than two months away from its spectacular close encounter with the sun. Already, the brightening comet has become a good target for backyard telescopes in the pre-dawn sky.

 

NASA | Tracking Energy through Space

This short video features commentary by David Sibeck, project scientist for the THEMIS mission, discussing a visualization of reconnection fronts.

 Taking advantage of an unprecedented alignment of eight satellites through the vast magnetic environment that surrounds Earth in space, including NASA's ARTEMIS and THEMIS, scientists now have comprehensive details of the energy's journey through a process that forms the aurora, called a substorm.
Their results showed that small events unfolding over the course of a millisecond can result in energy flows that last up to half an hour and cover an area 10 times larger than Earth.

 Trying to understand how gigantic explosions on the sun can create space weather effects involves tracking energy from the original event all the way to Earth. It's not unlike keeping tabs on a character in a play with many costume changes, because the energy changes form frequently along its journey: magnetic energy causes eruptions that lead to kinetic energy as particles hurtle away, or thermal energy as the particles heat up. Near Earth, the energy can change through all these various forms once again.

 Most of the large and small features of substorms take place largely in the portion of Earth's magnetic environment called the magnetotail. Earth sits inside a large magnetic bubble called the magnetosphere. As Earth orbits around the sun, the solar wind from the sun streams past the bubble, stretching it outward into a teardrop. The magnetotail is the long point of the teardrop trailing out to more than 1 million miles on the night side of Earth. The moon orbits Earth much closer, some 240,000 miles away, crossing in and out of the magnetotail.

 

NASA | Chasing Comet ISON

Comet ISON (C/2012 S1) may become a dazzling sight as it traverses the inner solar system in late 2013. During the weeks before its Nov. 28 close approach to the sun, the comet will be observable with small telescopes, and binoculars. Observatories around the world and in space will track the comet during its scorching trek around the sun. If ISON survives its searing solar passage, which seems likely but is not certain, the comet may be visible to the unaided eye in the pre-dawn sky during December.

This animation shows two views of comet ISON's path through the inner solar system. The first is a view following the comet along its orbit. The second is a view perpendicular to ISON's orbit. Like all comets, ISON is a clump of frozen gases mixed with dust. Often described as "dirty snowballs," comets emit gas and dust whenever they venture near enough to the sun that the icy material transforms from a solid to gas, a process called sublimation. Jets powered by sublimating ice also release dust, which reflects sunlight and brightens the comet.

 

ScienceCasts: The Strange Attraction of Hot Jupiters

An exotic class of exoplanets called "hot Jupiters" are even weirder than astronomers imagined. While these worlds may have Earth-like blue skies, new data show that they are anything but Earth-like.