Animations of Saturn’s aurorae

Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere.  The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the Solar wind pressure: the aurorae become brighter and move closer to the poles when the Solar wind pressure increases.

Credit: ESA/Hubble (M. Kornmesser & L. Calçada)

Stereoscopic View of the Lunar Surface

Apollo 11 carried a number of cameras for collecting data and recording various aspects of the mission, including a 35-mm surface close-up stereoscopic camera. It was designed for the highest possible resolution of a 3-inch square area with a flash illumination and fixed distance. Photography was accomplished by holding the camera on a walking stick against the object to be photographed. The camera was powered by four nickel-cadmium batteries that operated the motor-drive mechanism and an electronic flash strobe light.

There are many details seen in these pictures that were not known previously or that could not be seen with similar definition by astronauts Armstrong and Aldrin in their careful inspection of the lunar surface. The photographs taken on the mission with the close-up stereoscopic camera are of outstanding quality and show in detail the nature of the lunar surface material. From the photographs, information can be derived about the small-scale lunar surface geologic features and about processes occurring on the surface.

Image Credit: John Lloyd/NASA

July 20, 1969: One Giant Leap For Mankind

Astronaut Buzz Aldrin descending the ladder and stepping onto the Moon.  Neil Armstrong's “one small step” onto the lunar surface was actually a 3-foot jump down off the lunar module’s ladder to the ground.

Credit: NASA

July 20, 1969: One Giant Leap For Mankind

Astronaut Buzz Aldrin descending the ladder and stepping onto the Moon.  Neil Armstrong's “one small step” onto the lunar surface was actually a 3-foot jump down off the lunar module’s ladder to the ground.

Credit: NASA

Fundamental Studies in Droplet Combustion and FLame EXtinguishment in Microgravity (FLEX-2)

The Flame Extinguishment - 2 (FLEX-2) experiment is the second experiment to fly on the ISS which uses small droplets of fuel to study the special spherical characteristics of burning fuel droplets in space. The FLEX-2 experiment studies how quickly fuel burns, the conditions required for soot to form, and how mixtures of fuels evaporate before burning. Understanding how fuels burn in microgravity could improve the efficiency of fuel mixtures used for interplanetary missions by reducing cost and weight. It could also lead to improved safety measures for manned spacecraft.

  • More information: here

Credit: Reid Wiseman/NASA

(Source: youtube.com)

Titan’s Atmosphere

Titan is the largest moon of Saturn. It is the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found

Titan is primarily composed of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan’s surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in Titan’s polar regions.

The atmosphere is largely nitrogen; minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. Titan’s lower gravity means that its atmosphere is far more extended than Earth’s and about 1.19 times as massive. It supports opaque haze layers that block most visible light from the Sun and other sources and renders Titan’s surface features obscure. Atmospheric methane creates a greenhouse effect on Titan’s surface, without which Titan would be far colder. Conversely, haze in Titan’s atmosphere contributes to an anti-greenhouse effect by reflecting sunlight back into space, cancelling a portion of the greenhouse effect warming and making its surface significantly colder than its upper atmosphere.

Titan’s clouds, probably composed of methane, ethane or other simple organics, are scattered and variable, punctuating the overall haze.The findings of the Huygens probe indicate that Titan’s atmosphere periodically rains liquid methane and other organic compounds onto its surface. Clouds typically cover 1% of Titan’s disk, though outburst events have been observed in which the cloud cover rapidly expands to as much as 8%. One hypothesis asserts that the southern clouds are formed when heightened levels of sunlight during the southern summer generate uplift in the atmosphere, resulting in convection. This explanation is complicated by the fact that cloud formation has been observed not only after the southern summer solstice but also during mid-spring.

Image Credit: NASA/JPL/Space Science Institute

Saturn’s Rings and Enceladus

Saturn’s most distinctive feature is the thousands of rings that orbit the planet. Despite the fact that the rings look like continuous hoops of matter encircling the giant planet, each ring is actually made of tiny individual particles. Saturn’s rings consist largely of water ice mixed with smaller amounts of dust and rocky matter. Data from the Cassini spacecraft indicate that the environment around the rings is like an atmosphere, composed principally of molecular oxygen.

The ring system is divided into 5 major components: the G, F, A, B, and C rings, listed from outside to inside (but in reality, these major divisions are subdivided into thousands of individual ringlets). The F and G rings are thin and difficult to see, while the A, B, and C rings are broad and easily visible. The large gap between the A ring and and the B ring is called the Cassini division. One of Saturn’s moons, namely; Enceladus is the source of Saturn’s E-ring. The moon’s geyser-like jets create a gigantic halo of ice, dust, and gas that helps feed Saturn’s E ring.

Enceladus has a profound effect on Saturn and its environment. It’s the only moon in our solar system known to substantially influence the chemical composition of its parent planet. The whole magnetic environment of Saturn is weighed down by the material spewing from Enceladus, which becomes plasma — a gas of electrically charged particles.  This plasma, which creates a donut-shaped cloud around Saturn, is then snatched by Saturn’s A-ring, which acts like a giant sponge where the plasma is absorbed. 

Credit: , NASA/JPL/SSI

The Saturn V rocket launches Apollo 11 on its historic journey to the Moon on 16 July, 1969.

Apollo 11 Saturn V Launch (HD) from Mark Gray on Vimeo.

Apollo 11 Saturn V Launch (HD) from Mark Gray on Vimeo.

The Cassini spacecraft’s narrow angle camera captured Saturn’s moon Rhea as it gradually slipped into the planet’s shadow – an event known as “ingress”. 
Credit: NASA/JPL/Space Science Institute

The Cassini spacecraft’s narrow angle camera captured Saturn’s moon Rhea as it gradually slipped into the planet’s shadow – an event known as “ingress”.

Credit: NASA/JPL/Space Science Institute

Wolf-Rayet Star 124: Stellar Wind Machine

Resembling an aerial fireworks explosion, this dramatic picture of the energetic star WR124 reveals it is surrounded by hot clumps of gas being ejected into space at speeds of over 100,000 miles per hour. Also remarkable are vast arcs of glowing gas around the star, which are resolved into filamentary, chaotic substructures, yet with no overall global shell structure.
The massive, hot central star is known as a Wolf-Rayet star. This extremely rare and short-lived class of super-hot star (in this case 50,000 degrees Kelvin) is going through a violent, transitional phase characterized by the fierce ejection of mass. The blobs may result from the furious stellar wind that does not flow smoothly into space but has instabilities which make it clumpy.The surrounding nebula is estimated to be no older than 10,000 years, which means that it is so young it has not yet slammed into the gasses comprising the surrounding interstellar medium.

Image Credit:  Hubble Legacy Archive, NASA, ESA - Processing & Licence: Judy Schmidt

Wolf-Rayet Star 124: Stellar Wind Machine

Resembling an aerial fireworks explosion, this dramatic picture of the energetic star WR124 reveals it is surrounded by hot clumps of gas being ejected into space at speeds of over 100,000 miles per hour. Also remarkable are vast arcs of glowing gas around the star, which are resolved into filamentary, chaotic substructures, yet with no overall global shell structure.

The massive, hot central star is known as a Wolf-Rayet star. This extremely rare and short-lived class of super-hot star (in this case 50,000 degrees Kelvin) is going through a violent, transitional phase characterized by the fierce ejection of mass. The blobs may result from the furious stellar wind that does not flow smoothly into space but has instabilities which make it clumpy.The surrounding nebula is estimated to be no older than 10,000 years, which means that it is so young it has not yet slammed into the gasses comprising the surrounding interstellar medium.

Image Credit: Hubble Legacy Archive, NASA, ESA - Processing & Licence: Judy Schmidt

Extreme Ultraviolet Images of the Sun

Explanation of the colors used for SOHO extreme ultraviolet images of the Sun (that is, at wavelengths much shorter than “normal” ultraviolet wavelengths). Such radiation is also sometimes referred to as “soft” X-rays, since the boundary between X-rays and UV is rather arbitrarily set at about 100 Ångstroms.
All the images shown above were taken at wavelengths ten times shorter than the shortest visible wavelengths, imaging photons with ten times more energy than the most energetic visible photons. Since in the visible spectrum, shorter wavelengths correspond to blue and green light, and longer wavelengths to yellow, orange and red light, the shorter wavelength images are arbitrarily colored blue or green, and the longer wavelength images are colored amber or red.
The atoms (or, more accurately, since the atoms are missing one or more electrons, the ions) responsible for the wavelengths involved are indicated by Roman numerals which are one unit greater than the number of missing electrons. Hence, He II means helium ions which are missing one electron, and Fe XV means iron atoms which are missing fourteen electrons. The He II image looks different from the others, because it shows radiation from moderately hot helium atoms in the chromosphere; while the highly ionized iron atoms responsible for the other emissions are located in the lower corona.

Credit: SOHO - EIT Consortium, ESA, NASA, Courtney Seligman

Extreme Ultraviolet Images of the Sun

Explanation of the colors used for SOHO extreme ultraviolet images of the Sun (that is, at wavelengths much shorter than “normal” ultraviolet wavelengths). Such radiation is also sometimes referred to as “soft” X-rays, since the boundary between X-rays and UV is rather arbitrarily set at about 100 Ångstroms.

All the images shown above were taken at wavelengths ten times shorter than the shortest visible wavelengths, imaging photons with ten times more energy than the most energetic visible photons. Since in the visible spectrum, shorter wavelengths correspond to blue and green light, and longer wavelengths to yellow, orange and red light, the shorter wavelength images are arbitrarily colored blue or green, and the longer wavelength images are colored amber or red.

The atoms (or, more accurately, since the atoms are missing one or more electrons, the ions) responsible for the wavelengths involved are indicated by Roman numerals which are one unit greater than the number of missing electrons. Hence, He II means helium ions which are missing one electron, and Fe XV means iron atoms which are missing fourteen electrons. The He II image looks different from the others, because it shows radiation from moderately hot helium atoms in the chromosphere; while the highly ionized iron atoms responsible for the other emissions are located in the lower corona.

Credit: SOHO - EIT Consortium, ESA, NASA, Courtney Seligman

Cassini Celebrates 10 Years Exploring Saturn

It has been a decade since a robotic traveler from Earth first soared over rings of ice and fired its engine to fall forever into the embrace of Saturn. On June 30, the Cassini mission will celebrate 10 years of exploring the planet, its rings and moons.

  • More information about Cassini is available here & here

Credit: NASA/JPL-Caltech

The Mysterious X-ray Signal

A new study of the Perseus galaxy cluster, shown in this image, using NASA’s Chandra X-ray Observatory and 73 other clusters with ESA’s XMM-Newton has revealed a mysterious X-ray signal in the data. This signal is represented in the circled data points in the inset, which is a plot of X-ray intensity as a function of X-ray energy. The signal is also seen in over 70 other galaxy clusters using XMM-Newton. This unidentified X-ray emission line - that is, a spike of intensity at a very specific energy, in this case centered on about 3.56 kiloelectron volts (keV).
One intriguing possible explanation of this X-ray emission line is that it is produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter. While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

A paper describing the detection of this mysterious emission line was published in the June 20th issue of The Astrophysical Journal and a preprint is available online.
Credit: NASA/CXC/SAO/E.Bulbul, et al.

The Mysterious X-ray Signal

A new study of the Perseus galaxy cluster, shown in this image, using NASA’s Chandra X-ray Observatory and 73 other clusters with ESA’s XMM-Newton has revealed a mysterious X-ray signal in the data. This signal is represented in the circled data points in the inset, which is a plot of X-ray intensity as a function of X-ray energy. The signal is also seen in over 70 other galaxy clusters using XMM-Newton. This unidentified X-ray emission line - that is, a spike of intensity at a very specific energy, in this case centered on about 3.56 kiloelectron volts (keV).

One intriguing possible explanation of this X-ray emission line is that it is produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter. While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

  • A paper describing the detection of this mysterious emission line was published in the June 20th issue of The Astrophysical Journal and a preprint is available online.

Credit: NASA/CXC/SAO/E.Bulbul, et al.


Starting from the magnificent vista of the southern Milky Way we gradually zoom in on the huge star formation region NGC 3603 ending with an extreme close-up of the core of the central star cluster taken with the Wide Field Planetary Camera 2 (WFPC2) camera on the NASA/ESA Hubble Space Telescope.

Credit: NASA, ESA and Wolfgang Brandner (MPIA), Boyke Rochau (MPIA) and Andrea Stolte

Starting from the magnificent vista of the southern Milky Way we gradually zoom in on the huge star formation region NGC 3603 ending with an extreme close-up of the core of the central star cluster taken with the Wide Field Planetary Camera 2 (WFPC2) camera on the NASA/ESA Hubble Space Telescope.

Credit: NASA, ESA and Wolfgang Brandner (MPIA), Boyke Rochau (MPIA) and Andrea Stolte

Radar Observations of Asteroid 2014 HQ124

Radar data of asteroid 2014 HQ124 taken over for hours on June 8, 2014, when the asteroid was between 864.000 miles (1.39 million kilometers) and 902.00 miles (1,45 million kilometers) from Earth. The data reveals asteroid 2014 HQ124 to be an elongated, irregular object that is at least 1200 feet (370 meters) wide on it long axis. The radar was obtained using NASA’s 70 meters Goldstone antenna, the same antenna used for communicating with spacecraft in deep space. The Goldstone radar team paired with the Arecibo Observatory (Goldstone sending radar, Arecibo receiving) for the first five frames of this movie in order to collect higher quality data resulting in shaper images. The other frames were made by both sending and receiving with antennas at the Goldstone complex.

Credit: NASA/JPL

Radar Observations of Asteroid 2014 HQ124

Radar data of asteroid 2014 HQ124 taken over for hours on June 8, 2014, when the asteroid was between 864.000 miles (1.39 million kilometers) and 902.00 miles (1,45 million kilometers) from Earth. The data reveals asteroid 2014 HQ124 to be an elongated, irregular object that is at least 1200 feet (370 meters) wide on it long axis.

The radar was obtained using NASA’s 70 meters Goldstone antenna, the same antenna used for communicating with spacecraft in deep space. The Goldstone radar team paired with the Arecibo Observatory (Goldstone sending radar, Arecibo receiving) for the first five frames of this movie in order to collect higher quality data resulting in shaper images. The other frames were made by both sending and receiving with antennas at the Goldstone complex.

Credit: NASA/JPL