Tag Archives: NASA

A “Young” Supernova Remnant

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g306_wideAstronomers estimate that a supernova explosion occurs perhaps a couple of times a century in the Milky Way. The expanding blast wave and hot stellar debris slowly dissipate over hundreds of thousands of years, eventually mixing with and becoming indistinguishable from interstellar gas. The Swift satellite uncovered the previously unknown remains of a shattered star during an X-ray survey of the galaxy’s central regions. The new object, named G306.3-0.9 after it’s coordinates in the sky,is among the youngest of the 300+ known supernova remnants in the Milky Way. Analysis indicates that G306.3–0.9 is probably less than 2,500 years old. That would make it one of the 20 youngest supernova remnants identified.

This composite image of G306.3–0.9 (the blob in the lower left) was stitched together using data from Chandra X-ray observations (blue), infrared data acquired by the Spitzer Space Telescope (red and cyan) and radio observations (purple) from the Australia Telescope Compact Array.

G306_Swift_XRTjpgThe image on the left was taken in February, 2011, using Swift’s X-ray Telescope as part of the Galactic Plane Survey. The dots in the image indicate where X-rays struck the detector. Despite this short 8.5-minute exposure, the extended circular patch of G306.3–0.9 stands out quite nicely.

Image Credits: NASA

Titan’s Southern Sea

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Titan_southern_seaOr what’s left of it. The red outline traces the ancient shoreline. The largest remaining lake in Titan’s southern hemisphere, Ontario Lacus appears as black within that basin. The black indicated that it is filled with liquid.

This picture is assembled from images was obtained by the Cassini spacecraft’s radar instrument during July, 2009, and January, 2010. Mission scientists estimate the ancient sea was possibly as large as 475 X 280 km across but probably only a few hundred meters deep. Ontario Lacus is about 80 X 235 km and probably on the order of 10 meters deep. Seas may have covered large parts of Titan’s southern hemisphere less than 50,000 years ago.

Titan, Saturn’s largest moon, is the only body in the Solar System other than the Earth that has large open bodies of liquid. The temperature on Titan runs around 94 K (about -290 °F), so that liquid is not water. It’s methane and ethane. While over one hundred lakes and three seas are seen around Titan’s north pole, the south pole only has a few small lakes. It’s been suggested that cycles similar to Milankovich cycles on Earth cause long-term transfers of liquid hydrocarbons between the poles and that it’s now the north poles turn to keep the bulk of the liquids. Less than 50,000 years ago, the cycle may have reversed, nearly emptying the southern seas.

Image Credit: NASA

The Big Dipper As Seen From Space

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BigDipper_JunoThe Juno spacecraft is on its way to Jupiter. It’s taking a roundabout route, and it’s currently headed toward Earth for a slingshot maneuver that will send out to its destination. Once there, the spacecraft will orbit the planet’s poles 33 times and use its nine instruments to image and probe beneath the gas giant’s cloud cover.

One of those instruments, JunoCam, will be used for closeups of the atmosphere. In order to certify the camera in flight, Juno’s mission planners aimed the camera at a familiar celestial landmark, the Big Dipper.

Image Credit: NASA

A Class-X Solar Flare

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SDO_May_13_XFlareThe sun erupted with an X1.7-class solar flare on 12 May, 2013. This is a blend of a pair of images of the flare from the Solar Dynamics Observatory. One image shows light in the 17.1 nm wavelength, the other in 13.1 nm. ”X-class” denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, and so on.

Solar flares are massive bursts of radiation. The Earth’s atmosphere provides protection to us at ground level from harmful radiation; however, intense flares can disturb the layer of the atmosphere in the layer where communications signals travel. This disrupts the radio signals for as long as the flare is ongoing—the radio blackout associated with this flare has since subsided much to the joy of amateur radio operators like me.

Image Credit: NASA

Thunder and Lightning on Saturn

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head_to_tailThis collection of images from the Cassini spacecraft orbiting Saturn shows the evolution of a massive thunder storm that circled all the way around the planet and fizzled out when it ran into its own tail. The storm was first detected on 5 December, 2010. It developed a head of bright clouds which began rapidly moving west and also spawned a much slower moving clockwise-spinning vortex.

The bright clouds at the head of the storm are indicated with red triangles. Yellow triangles mark the vortex.

The top image was taken not long after the start of the storm on 22 January, 2011. It shows the bright head of the storm just ahead of the vortex by about 40,000 km. The next image from 5 May shows that the head of the storm had traveled around the planet and started approaching the vortex from the east. The storm’s body had stretched over 220,000 km, and the head was within about 80,000 km of the vortex. That image also shows that the  vortex was losing steam compared to the head of the storm. The third image was taken on 14 June. The head of the storm had made its way roughly 290,000 km—almost entirely around the planet, and it was about to catch up with the vortex. The head of the storm was just 14,000 km east of the vortex. The bottom image, from 12 July, 2011, shows that the storm fizzled once the head and vortex met. Only the vortex remains; the bright cloud has disappeared. By late August, the storm stopped generating lightning for good.

These are false color images with the colors denoting the altitudes of the clouds. Red data is from a wavelength of radiation that penetrates the atmosphere deep down to the top of the tropospheric cloud deck (750 nm). Green represents an intermediate wavelength above the troposphere (728 nm). Blue is for a wavelength that penetrates only to the top of tropospheric haze (890 nm). White is for thick clouds at high altitudes.

Image Credit: NASA

Beautiful Plumage

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If you google “beautiful plumage,” the first hit is the YouTube video of the Monthy Python Dead Parrot sketch. That’s what I first thought of when I saw the headline on the NASA site for this photo of Saturn’s moon Enceladus. I had to chuckle.beautiful_plumage

This copy is from NASA’s caption of the picture—

Like a proud peacock displaying its tail, Enceladus shows off its beautiful plume to the Cassini spacecraft’s cameras.
Enceladus (313 miles, or 504 kilometers across) is seen here illuminated by light reflected off Saturn.
This view looks toward the Saturn-facing side of Enceladus. North on Enceladus is up and rotated 45 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 18, 2013.
The view was acquired at a distance of approximately 483,000 miles (777,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 173 degrees. Image scale is 3 miles (5 kilometers) per pixel.

Image Credit: NASA

A Shell in a Fish

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supernova_shellThese thin wisps of gas are an object known as SNR 0519. The blood-red clouds are the remains from a violent explosion of a star as a supernova seen about 600 years ago. The star that exploded is known to have been a white dwarf star—a Sun-like star in the final stages of its life.

SNR 0519 is over 150 000 light-years from Earth in the southern constellation of Dorado (The Dolphinfish), a constellation that also contains most of our neighboring galaxy the Large Magellanic Cloud, a region of the sky is full of intriguing and beautiful deep sky objects. The Large Magellanic Cloud orbits the Milky Way galaxy as a satellite and is the fourth largest in our group of galaxies.

Image Credit: NASA/ESA

Gamma Rays!

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Fermi_LAT_GRB_673Just after 07:47 UTC last Saturday, the Gamma-ray Burst Monitor (GBM) aboard the Fermi satellite triggered on an eruption of high-energy light in the constellation Leo. Click on the image to see an animation showing a more detailed Fermi Large Area Telescope view. GRB 130427A produced the highest-energy light ever detected from gamma ray burst. The sequence shows high-energy (100 MeV to 100 GeV) gamma rays from a 20-degree-wide region of the sky starting three minutes before the burst to 14 hours after. After a one-second spike, the burst’s output remained relatively quiet for the next 15 seconds while Fermi‘s GBM showed bright, variable lower-energy emission. Then the burst re-brightened in the LAT over the next few minutes and remained bright for almost half a day. The record-setting blast of gamma rays came from a dying star in a distant galaxy roughly 3.6 billion light-years away.

Fermi’s Large Area Telescope (LAT) recorded one gamma ray with an energy of at least 94 billion electron volts (GeV), or some 35 billion times the energy of visible light, and about three times greater than any previous GRB. The GeV emission from the burst lasted for several hours, and it remained detectable by the LAT for the most of the day, making it the longest gamma-ray emission from a GRB detected to date.

The burst occurred as NASA’s Swift satellite was slewing between targets, which delayed its Burst Alert Telescope’s (BAT) detection by less than a minute. (The BAT is a wide-angle detector that can quickly determine the bearing to a gamma ray source. I designed the low-noise power regulators that feed the detector array in the BAT.) The burst was detected in optical, infrared and radio wavelengths by ground-based observatories using the rapid, accurate position from Swift.

Swift_XRTSwift‘s X-Ray Telescope took this image of GRB 130427A at 07:50 UTC on 27 April, moments after Swift and Fermi triggered on the GRB.

Gamma-ray bursts are the universe’s most luminous explosions. We believe that most occur when massive stars run out of nuclear fuel and collapse under their own weight. As the core collapses into a black hole, jets of material explode outward at almost the speed of light.

Image Credits: NASA

Who’s On First?

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whosonfirsOr which spacecraft is being used where in our exploration of the Universe? For now, each of the inner planet has at least one robotic explorer, and several spacecraft are monitoring the Sun. There are missions mapping Earth’s Moon, a few are chasing asteroids and comets, and one is orbiting Saturn. Some are heading out into deep space as others look out at the Universe beyond the Solar System. This map shows some details. (Click to embiggen.) The inner Solar System is depicted on the upper right, and the outer Solar System is on the lower left. Future spacecraft milestones, some are listed along the bottom of the graphic, include Dawn reaching Ceres, the largest object in the asteroid belt, and New Horizons reaching Pluto, both in 2015.

Image Credit: The Planetary Society (Creative Commons License)

Incoming Comet ISON

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ISON_HubbleThis Hubble Space Telescope image of Comet ISON (C/2012 S1) was photographed earlier this month when the comet was just inside Jupiter’s orbit at a distance of around 620 million km from the Sun (635 million km from Earth).

Even that far out, the comet is already becoming active as sunlight warms the surface and frozen volatiles sublimate. Analysis of the dust coma surrounding the solid, icy nucleus shows a strong stream of dust particles coming off the Sun-facing side of the comet.

Preliminary measurements from Hubble images suggest that the ISON’s nucleus isn’t much more than than 5 or 6 km across. That’s tiny considering the high level of activity observed thus far. Astronomers are measuring the activity level of this comet now in order to predict the comet’s activity when it skims a bit more than 1,000,000 km above the sun’s surface on Thanksgiving.

The comet’s dusty coma, the head of the comet, is approximately 5,000 km across, and its dust tail stretches more than 90,000 km, which is wider than Hubble’s field of view.

This image was taken in visible light. The blue false color was added to highlight details in the comet structure.

Image Credit: NASA

Gamma Rays for Christmas

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GRB_111209AThe gamma ray burst (GRB) from GRB 111209A (aka the Christmas Burst) was detected in early December, 2011. The blast produced high-energy emission for an astonishing seven hours, the longest-duration GRB ever observed. This false-color image shows the event as captured by the X-ray Telescope aboard NASA’s Swift satellite. Because the distance to the burst was not measured initially, astronomers came up with a couple of radically different interpretations. In one scenario, a solitary neutron star in our own galaxy shredded and accreted an approaching comet-like body. In the other, a neutron star spiraled into and was eaten by a giant star in a distant galaxy. Now, a third explanation has been advanced. After a measurement of the Christmas Burst’s host galaxy, it appears that the GRB resulted from the collapse and explosion of a supergiant star hundreds of times larger than the sun.

Image Credit: NASA

Saturn and Meteors

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Saturn_meteorsThe solar system is full of small, speeding objects. These objects frequently pummel planetary bodies. Saturn’s rings are the only location besides Earth, the Moon, and Jupiter where astronomers have been able to observe impacts as they occur. The meteoroids at Saturn are estimated to range from about a centimeter up to several meters in size. NASA’s Cassini spacecraft has found the first direct evidence of small meteoroids breaking into streams of rubble as they crashed into Saturn’s rings.

The Saturnian equinox in summer 2009 was an excellent time to see the debris kicked up by meteoroid impacts. The very low sun angle on the rings caused the clouds of debris to stand out brightly against the darkened rings. The tiny particles forming these clouds have a range of orbital speeds around Saturn, and the clouds they form are pulled into diagonal, extended bright streaks as can be seen in the five pictures above.

The objects hitting the rings in these photos were probably roughly the same size as the Russian meteor of last February.

Image Credits: NASA

Water, Water, Everywhere:

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Nor any drop to drink.Jupiter_water

Astronomers have finally found direct proof that almost all water present in Jupiter’s stratosphere, an intermediate atmospheric layer, was delivered by comet Shoemaker-Levy 9, which struck the planet in 1994. The findings are based on new data from the Herschel space observatory and reveal more water in Jupiter’s southern hemisphere, where the impacts occurred, than in the north. Herschel is a European Space Agency mission.

Jupiter_Shoemaker_LevyThe origin of water in the upper atmospheres of the solar system’s giant planets has been a hot topic among planetary astronomers since the late ’90s. Astronomers were quite surprised when water was found in the stratospheres of Jupiter, Saturn, Uranus and Neptune by ESA’s Infrared Space Observatory.

The composite photo at left was assembled from separate images of Jupiter and comet Shoemaker-Levy 9 taken by the Hubble Space Telescope in 1994.

Image Credits: Top, ESA. Left, NASA

A Cosmic Puff Ball

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sn1006This cosmic puff ball is the remains of the brightest supernova in recorded history. In AD 1006, a supernova lit up the nighttime skies  and was seen by observers China, Egypt, Iraq, Italy, Japan, and Switzerland. This image was assembled from data at three different wavelength  of X-rays taken from orbit by Chandra X-ray Observatory. The debris cloud from what is now called the SN 1006 supernova remnant is about 60 light-years across. It’s the remains of a white dwarf star that was part of a binary star system. The white dwarf gradually captured ate its companion star, and the increase in mass caused a thermonuclear explosion. Because the supernova remnant is about 7,000 light-years away, that explosion actually happened 7,000 years before the light reached Earth in 1006, or in roughly 6000 BC.

Image Credit: NASA

A Year’s Worth of Sun

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Timelapse_SunThis picture is a composite of 25 separate images taken during the year from 16 April, 2012, to 15 April, 2013, as seen by the Solar Dynamics Observatory at a wavelength of 17.1 nm.  It shows the areas on the sun where active regions were most common during that part of the 11 year solar cycle.

Image Credit: NASA

A Ridge on Mercury

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converted PNM fileThis isn’t a picture of the Moon. It’s the planet Mercury as seen by the Mariner 10 spacecraft almost 40 years ago. The Antoniadi Ridge, which is over 450 km long, runs down the right side of the image. The ridge cross a large crater (80 km in diameter) and in turn appears to be interrupted by an irregular depression on the crater’s floor. The ridge extends across plain to the north and south of the crater.

Mariner 10 explored Venus in February, 1974, on the way to three encounters with Mercury in March and September, 1974, and in March, 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA

A Horsehead of a Different Color

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horseheadofadifferentcolorhorsehead_cThe Hubble Space Telescope was launched 23 years ago. Astronomers have used Hubble to make the above photograph of the iconic Horsehead Nebula in infrared light to mark the anniversary. The Horsehead Nebula has been a staple image in astronomy books for a century or so. While it’s shadowy in visible light (at left), it appears transparent and ethereal when photographed at infrared wavelengths as it pops out against a backdrop of stars and distant galaxies visible in infrared light.

Image Credit: NASA

Jupiter from Saturn

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Jupiter_from_SaturnThis is Jupiter as seen from Saturn’s orbit by the Cassini spacecraft. Cassini‘s cameras were specially designed to photograph the nearby bodies in the Saturn system, but as this image demonstrates, the cameras are pretty good telescopes. At the time this picture was taken, the distance to Jupiter was more than 11 times the distance between Earth and the Sun, a range of around 1.8 billion kilometers from Jupiter, or slightly farther than the average Earth-Saturn distance. Scale in the original image was about 10,000 kilometers per pixel—the Earth would show up as a single pixel at that scale.

Images taken using red, green and blue spectral filters were combined to create this natural color picture. The picture was contrast enhanced and magnified by a factor of two and a half to enhance the visibility of cloud features on the planet.

Image Credit: NASA

Ants in Space

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ant_nebulaThis Hubble Space Telescope image of the Ant Nebula may shed new light on the future of our Sun. When seen through ground based telescopes, the Ant Nebula (aka Mz3) resembles the head and thorax of an insect. This image, with 10 times the resolution and 100 times better detail, shows the ant’s body as a pair of fiery lobes extending from a dying, Sun-like star.

The image and other pictures of dying stars in what are called planetary nebulae call into question some theories about what happens to dying stars. Our Sun’s fate will probably be much more interesting, complex and dramatic than astronomers previously believed, but we’ll have to wait several billion years to find out.

The ejection of gas from the dying star in the Ant Nebula does not show the chaos one might expect from an ordinary explosion. The patterns are quite symmetrical. It could be that the central star has a closely orbiting companion whose gravitational tidal forces shape the outflowing gas. Electrically charged winds, much like those in our Sun’s solar wind but millions of times denser and moving at speeds up to 1,000 kilometers per second from the star, follow the twisted field lines on their way out into space. Perhaps as the dying star spins, its strong magnetic fields are wound up into complex shapes like noodles being stirred.

Image Credit: NASA

Stingray!

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Stingray_nebulaThe Stingray nebula (Hen-1357) is the youngest known planetary nebula. This Hubble image (click to embiggen) captures the bright central star is in the middle of the green ring of gas. A companion star is above it at 10 o’clock. A green spur of gas forms a faint bridge to the companion star as a result of gravitational attraction. There’s also a ring of green gas surrounding the central star and bubbles of gas at the lower left and upper right of the ring. The wind of stellar material propelled by radiation from the hot central star has created enough pressure to blow out holes in the ends of the bubbles, allowing gas to escape. The bright red, curved lines of gas are heated by the collision of the central star’s wind hitting the bubbles’ walls. The nebula is about 130 times the diameter of our Solar System. However, since it’s 18,000 light-years away, it appears only as big as a dime viewed a mile away. The colors in this picture are actual colors emitted by nitrogen (red), oxygen (green), and hydrogen (blue).

The Stingray is located in the southern constellation Ara (the Altar). As to why it’s called the Stingray … Beats me. I doesn’t look much like an old Corvette.

Image Credit: NASA

Triangulum

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M33M33, the Triangulum Galaxy, is a favorite of astronomers, amateur and professional alike, because of its orientation and relative proximity to us. It is the second nearest spiral galaxy to our Milky Way (after M31, the Andromeda Galaxy) and a part of the “local group” of galaxies. From our perspective, M33′s disk appears at moderate inclination. That permits us to see its internal structure clearly. M31 is oriented nearly edge-on.

The Galaxy Evolution Explorer took this picture of M33 in ultraviolet wavelengths. Ultraviolet imaging mostly shows us emissions from the atmospheres of hot, young stars. Young in this case means only a few hundred million years old. Observations of M33 allow astronomers to compare the population of young, massive stars with other components of the galaxy such as interstellar dust and gas. The clouds contain the raw material from which stars form. This comparison gives us insight into the star formation process as it occurs throughout an entire spiral galaxy and is an important resource for studies of galaxy evolution.

Image Credit: NASA

Today’s Solar Flare

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Flare20130411NASA’s Solar Dynamics Observatory captured this image of an M6.5 class flare at 07:16 UTC today. This image shows a combination of light in wavelengths of 13.1 and 17.1 nm. The M6.5 flare was associated with an Earth-directed coronal mass ejection (CME), a kind of solar event that can send billions of tons of solar particles into space that can reach Earth one to three days later. CMEs can affect electronic systems in satellites and on the ground. NASA models show the CME leaving the sun at over 600 miles per second.

Image Credit: NASA