Ganymede and Callisto are similar in size and are made of a similar mixture of ice and rock, but data from the Galileo and Voyager spacecraft show that they look different at the surface and on the inside. Just like Earth and Venus, Ganymede and Callisto are twins, and understanding how they were born the same and grew up to be so different is of tremendous interest to planetary scientists.

Ganymede and Callisto’s evolutionary paths diverged about 3.8 billion years ago during the Late Heavy Bombardment, the phase in lunar history dominated by large impact events. Impacts during this period melted Ganymede so thoroughly and deeply that the heat could not be quickly removed. All of Ganymede’s rock sank to its center the same way that all the chocolate chips sink to the bottom of a melted carton of ice cream. Callisto received fewer impacts at lower velocities and avoided complete melting. Ganymede is closer to Jupiter and therefore is hit by twice as many icy impactors as Callisto, and the impactors hitting Ganymede have a higher average velocity.

Image Credit: NOAA/GSD

(Source: swri.org)

Happy Yuri’s Night!

Happy Yuri’s Night!

The planetary nebula Abell 33 captured using ESO’s Very Large Telescope

Astronomers using ESO’s Very Large Telescope in Chile have captured this eye-catching image of planetary nebula Abell 33. Created when an aging star blew off its outer layers, this beautiful blue bubble is, by chance, aligned with a foreground star, and bears an uncanny resemblance to a diamond engagement ring. This cosmic gem is unusually symmetric, appearing to be almost perfectly circular on the sky.

Credit: ESO

The planetary nebula Abell 33 captured using ESO’s Very Large Telescope

Astronomers using ESO’s Very Large Telescope in Chile have captured this eye-catching image of planetary nebula Abell 33. Created when an aging star blew off its outer layers, this beautiful blue bubble is, by chance, aligned with a foreground star, and bears an uncanny resemblance to a diamond engagement ring. This cosmic gem is unusually symmetric, appearing to be almost perfectly circular on the sky.

Credit: ESO

NASA’s OCO-2 Brings Sharp New Focus on Global Carbon

Simply by breathing, humans have played a small part in the planet-wide balancing act called the carbon cycle throughout our existence. However, in the last few hundred years, we have taken a larger role. Our activities, such as fossil fuel burning and deforestation, are pushing the cycle out of its natural balance, adding more and more carbon dioxide to the atmosphere.
Natural processes are working hard to keep the carbon cycle in balance by absorbing about half of our carbon emissions, limiting the extent of climate change. There’s a lot we don’t know about these processes, including where they are occurring and how they might change as the climate warms. To understand and prepare for the carbon cycle of the future, we have an urgent need to find out.
This animation shows the Orbiting Carbon Observatory-2, the first NASA spacecraft dedicated to studying carbon dioxide in Earth’s atmosphere. In July 2014, NASA will launch the Orbiting Carbon Observatory-2 (OCO-2) to study the fate of carbon dioxide worldwide. OCO-2 will not be the first satellite to measure carbon dioxide, but it’s the first with the observational strategy, precision, resolution and coverage needed to answer these questions about these little-monitored regions.
OCO-2’s scientific instrument uses spectrometers, which split sunlight into a spectrum of component colors, or wavelengths. Like all other molecules, carbon dioxide molecules absorb only certain colors of light, producing a unique pattern of dark features in the spectrum. The intensity of the dark features increases as the number of carbon dioxide molecules increases in the air that the spectrometer is looking through.
OCO-2 will collect 24 measurements a second over Earth’s sunlit hemisphere, totaling more than a million measurements each day. Fewer than 20 percent of these measurements will be sufficiently cloud-free to allow an accurate estimate of carbon dioxide, but that number will still yield 100 to 200 times as many measurements as the currently observing Japanese Greenhouse gases Observing SATellite (GOSAT) mission. The measurements will be used as input for global atmospheric models.
For more information about OCO-2, visit: https://oco.jpl.nasa.gov


Image Credit: NASA/JPL-Caltech

NASA’s OCO-2 Brings Sharp New Focus on Global Carbon

Simply by breathing, humans have played a small part in the planet-wide balancing act called the carbon cycle throughout our existence. However, in the last few hundred years, we have taken a larger role. Our activities, such as fossil fuel burning and deforestation, are pushing the cycle out of its natural balance, adding more and more carbon dioxide to the atmosphere.

Natural processes are working hard to keep the carbon cycle in balance by absorbing about half of our carbon emissions, limiting the extent of climate change. There’s a lot we don’t know about these processes, including where they are occurring and how they might change as the climate warms. To understand and prepare for the carbon cycle of the future, we have an urgent need to find out.

This animation shows the Orbiting Carbon Observatory-2, the first NASA spacecraft dedicated to studying carbon dioxide in Earth’s atmosphere. In July 2014, NASA will launch the Orbiting Carbon Observatory-2 (OCO-2) to study the fate of carbon dioxide worldwide. OCO-2 will not be the first satellite to measure carbon dioxide, but it’s the first with the observational strategy, precision, resolution and coverage needed to answer these questions about these little-monitored regions.

OCO-2’s scientific instrument uses spectrometers, which split sunlight into a spectrum of component colors, or wavelengths. Like all other molecules, carbon dioxide molecules absorb only certain colors of light, producing a unique pattern of dark features in the spectrum. The intensity of the dark features increases as the number of carbon dioxide molecules increases in the air that the spectrometer is looking through.

OCO-2 will collect 24 measurements a second over Earth’s sunlit hemisphere, totaling more than a million measurements each day. Fewer than 20 percent of these measurements will be sufficiently cloud-free to allow an accurate estimate of carbon dioxide, but that number will still yield 100 to 200 times as many measurements as the currently observing Japanese Greenhouse gases Observing SATellite (GOSAT) mission. The measurements will be used as input for global atmospheric models.

For more information about OCO-2, visit: https://oco.jpl.nasa.gov

Image Credit: NASA/JPL-Caltech

Photo by Maynard Pittendreigh
Comet Ikeya–Seki, formally designated C/1965 S1, 1965 VIII, and 1965f, was a long-period comet discovered independently by Kaoru Ikeya and Tsutomu Seki. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km above the Sun’s surface, and would probably become extremely bright.
Comets can defy all predictions, but Ikeya–Seki performed as expected. As it approached perihelion observers reported that it was clearly visible in the daytime sky next to the Sun. In Japan, where it reached perihelion at local noon, it was seen shining at magnitude −10. It proved to be one of the brightest comets seen in the last thousand years, and is sometimes known as the Great Comet of 1965.
The comet was seen to break into three pieces just before its perihelion passage. The three pieces continued in almost identical orbits, and the comet re-appeared in the morning sky in late October, showing a very bright tail. By early 1966, it had faded from view as it receded into the outer solar system.
Ikeya–Seki is a member of the Kreutz Sungrazers, which are suggested to be fragments of a large comet which broke up in 1106

Photo by Maynard Pittendreigh

Comet Ikeya–Seki, formally designated C/1965 S1, 1965 VIII, and 1965f, was a long-period comet discovered independently by Kaoru Ikeya and Tsutomu Seki. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km above the Sun’s surface, and would probably become extremely bright.

Comets can defy all predictions, but Ikeya–Seki performed as expected. As it approached perihelion observers reported that it was clearly visible in the daytime sky next to the Sun. In Japan, where it reached perihelion at local noon, it was seen shining at magnitude −10. It proved to be one of the brightest comets seen in the last thousand years, and is sometimes known as the Great Comet of 1965.

The comet was seen to break into three pieces just before its perihelion passage. The three pieces continued in almost identical orbits, and the comet re-appeared in the morning sky in late October, showing a very bright tail. By early 1966, it had faded from view as it receded into the outer solar system.

Ikeya–Seki is a member of the Kreutz Sungrazers, which are suggested to be fragments of a large comet which broke up in 1106


Comet Arend–Roland was discovered on November 8, 1956, by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III. Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the ‘C/’ indicating it was a non-periodic comet and the R1 showing it was the first comet reported as discovered in the half-month designated by R. The last is equivalent to the period September 1–15.
Astronomer Carl Sagan relates an anecdote on page 80 of his book Cosmos about being on duty in an observatory near Chicago in 1957 when a late night phone call from an inebriated man asked what was the “fuzzy thing” they were seeing in the sky. Sagan told the man it was a comet (Arend–Roland). The man asked what a comet was, and Sagan answered that it was “a snowball, one mile wide”. After a long pause, the man said, quoting Sagan: “Lemme talk to a real ‘shtronomer!”.

Comet Arend–Roland was discovered on November 8, 1956, by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III. Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the ‘C/’ indicating it was a non-periodic comet and the R1 showing it was the first comet reported as discovered in the half-month designated by R. The last is equivalent to the period September 1–15.

Astronomer Carl Sagan relates an anecdote on page 80 of his book Cosmos about being on duty in an observatory near Chicago in 1957 when a late night phone call from an inebriated man asked what was the “fuzzy thing” they were seeing in the sky. Sagan told the man it was a comet (Arend–Roland). The man asked what a comet was, and Sagan answered that it was “a snowball, one mile wide”. After a long pause, the man said, quoting Sagan: “Lemme talk to a real ‘shtronomer!”.

At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandless, pictured above, was floating free in space. McCandless and fellow NASAastronaut Robert Stewart were the first to experience such an “untethered space walk" during Space Shuttle mission 41-B in 1984. The MMU works by shooting jets of nitrogen and has since been used to help deploy and retrieve satellites. With a mass over 140 kilograms, an MMU is heavy on Earth, but, like everything, is weightless when drifting in orbit. The MMU was replaced with the SAFER backpack propulsion unit.

Credit: STS-41B, NASA

Suppose you had a single hydrogen atom and at a particular instant plotted the position of its electron. Soon afterwards, you do the same thing, and find that it is in a new position. You have no idea how it got from the first place to the second. You keep on doing this over and over again, and gradually build up a sort of 3D map of the places that the electron is likely to be found.
The Heisenberg Uncertainty Principle  says - loosely - that you can’t know with certainty both where an electron is and where it’s going next. That makes it impossible to plot an orbit for an electron around a nucleus, but we have a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom’s nucleus.
In the hydrogen case, the electron can be found anywhere within a spherical space surrounding the nucleus. Such a region of space is called an orbital. Orbits and orbitals sound similar, but they have quite different meanings. It is essential that you understand the difference between them. You can think of an orbital as being the region of space in which the electron lives. The GIF animation shows the probability densities for the electron of a hydrogen atom in different quantum states. These orbitals form an orthonormal basis for the wave function of the electron. These shapes are intended to describe the angular forms of regions in space where the electrons occupying the orbital are likely to be found.

Suppose you had a single hydrogen atom and at a particular instant plotted the position of its electron. Soon afterwards, you do the same thing, and find that it is in a new position. You have no idea how it got from the first place to the second. You keep on doing this over and over again, and gradually build up a sort of 3D map of the places that the electron is likely to be found.

The Heisenberg Uncertainty Principle  says - loosely - that you can’t know with certainty both where an electron is and where it’s going next. That makes it impossible to plot an orbit for an electron around a nucleus, but we have a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom’s nucleus.

In the hydrogen case, the electron can be found anywhere within a spherical space surrounding the nucleus. Such a region of space is called an orbital. Orbits and orbitals sound similar, but they have quite different meanings. It is essential that you understand the difference between them. You can think of an orbital as being the region of space in which the electron lives. The GIF animation shows the probability densities for the electron of a hydrogen atom in different quantum states. These orbitals form an orthonormal basis for the wave function of the electron. These shapes are intended to describe the angular forms of regions in space where the electrons occupying the orbital are likely to be found.

(Source: goo.gl)

" We are the local embodiment of a Cosmos grown to selfawareness. We have begun to contemplate our origins: starstuff pondering the stars; organized assemblages of ten billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose." 
— Carl Sagan

" We are the local embodiment of a Cosmos grown to selfawareness. We have begun to contemplate our origins: starstuff pondering the stars; organized assemblages of ten billion billion billion atoms considering the evolution of atoms; tracing the long journey by which, here at least, consciousness arose."

Carl Sagan

Fox Recruits Slavoj Zizek to Head ‘Cosmos’ Spin-Off

After the widespread popularity and critical acclaim of the “Cosmos” reboot with astophysicist Neil deGrasse Tyson, Fox has announced work on a sister-project entitled “The Real” to be hosted by Slovenian theorist Slavoj Zizek. Unlike “Cosmos”, which centers around physics and other hard sciences, “The Real” will be an expansive survey of the development of human culture and civilization. It is slated to air early in 2015.
“We’re extremely happy to be working with Mr. Zizek,” 21st Century Fox said in a press release, “his sharp wit and entertainment prowess will be an invaluable asset in telling the story of humanity.”
In an interview with Critical-Theory, Fox programming director Theresa Jenkins told us that Fox had been looking to work with Zizek since the critical acclaim of “The Pervert’s Guide to Cinema.” Zizek, Jenkins tells us, was vetted to replace Alan Colmes after his 2009 departure from “Hannity & Colmes.”
“It just didn’t work out,” Jenkins notes, “Slavoj refused to be on air in a suit. He even showed up to the interview in a t-shirt covered in stains and beard dandruff.”
Some Fox executives had concerns about letting an avowed Communist be on network television. Zizek even met with Rubert Murdoch, who allegedly “hit it off” with the theorist. “There’s just something about the way he slobbers the word ‘billions,” Murdoch was quoted as saying.
We also caught up with Zizek, who is “totally excited” for the project. “You know, there is something I deeply respect about Murdoch’s authoritarian attitude – it very much reminds me of Stalin.”
“They are letting me say whatever I want,” he continues, “in part because they think I’m a clown. I hope I can leverage this to achieve my real dream – writing a book with Sarah Palin. I wish to call it ‘Restoring America: Family, Faith, and Fantasy.’”
You can watch the full interview with Zizek here.

via critical-theory

Fox Recruits Slavoj Zizek to Head ‘Cosmos’ Spin-Off

After the widespread popularity and critical acclaim of the “Cosmos” reboot with astophysicist Neil deGrasse Tyson, Fox has announced work on a sister-project entitled “The Real” to be hosted by Slovenian theorist Slavoj Zizek. Unlike “Cosmos”, which centers around physics and other hard sciences, “The Real” will be an expansive survey of the development of human culture and civilization. It is slated to air early in 2015.

“We’re extremely happy to be working with Mr. Zizek,” 21st Century Fox said in a press release, “his sharp wit and entertainment prowess will be an invaluable asset in telling the story of humanity.”

In an interview with Critical-Theory, Fox programming director Theresa Jenkins told us that Fox had been looking to work with Zizek since the critical acclaim of “The Pervert’s Guide to Cinema.” Zizek, Jenkins tells us, was vetted to replace Alan Colmes after his 2009 departure from “Hannity & Colmes.”

“It just didn’t work out,” Jenkins notes, “Slavoj refused to be on air in a suit. He even showed up to the interview in a t-shirt covered in stains and beard dandruff.”

Some Fox executives had concerns about letting an avowed Communist be on network television. Zizek even met with Rubert Murdoch, who allegedly “hit it off” with the theorist. “There’s just something about the way he slobbers the word ‘billions,” Murdoch was quoted as saying.

We also caught up with Zizek, who is “totally excited” for the project. “You know, there is something I deeply respect about Murdoch’s authoritarian attitude – it very much reminds me of Stalin.”

“They are letting me say whatever I want,” he continues, “in part because they think I’m a clown. I hope I can leverage this to achieve my real dream – writing a book with Sarah Palin. I wish to call it ‘Restoring America: Family, Faith, and Fantasy.’”

You can watch the full interview with Zizek here.

via critical-theory

teded:

Astronomer Johannes Kepler proved that planetary orbits are elliptical and that the Sun is not the center of the orbit.
From the TED-Ed Lesson Reasons for the seasons - Rebecca Kaplan
Animation by Marc Christoforidis

teded:

Astronomer Johannes Kepler proved that planetary orbits are elliptical and that the Sun is not the center of the orbit.

From the TED-Ed Lesson Reasons for the seasons - Rebecca Kaplan

Animation by Marc Christoforidis

Coronal loop

The corona is the outer part of the solar atmosphere. Its name derives from the fact that, since it is extremely tenuous with respect to the lower atmosphere, it is visible in the optical band only during the solar eclipses as a faint crown (corona in Latin) around the black moon disk. When inspected through spectroscopy the corona reveals unexpected emission lines, which were first identified as due to a new element (coronium) but which were later ascertained to be due to high excitation states of iron. It became then clear that the corona is made of very high temperature gas, hotter than 1 MK(megakelvin). Almost all the gas is fully ionized there and thus interacts effectively with the ambient magnetic field. It is for this reason that the corona appears so inhomogeneous when observed in the X-ray band, in which plasma at million degrees emits most of its radiation. In particular, the plasma is confined inside magnetic flux tubes which are anchored on both sides to the underlying photosphere. When the confined plasma is heated more than the surroundings, its pressure and density increase. Since the tenuous plasma is optically thin, the intensity of its radiation is proportional to the square of the density, and the tube becomes much brighter than the surrounding ones and looks like a bright closed arch: a coronal loop.
Coronal Loops: Observations and Modeling of Confined Plasma

Credit: Fabio Reale

Coronal loop

The corona is the outer part of the solar atmosphere. Its name derives from the fact that, since it is extremely tenuous with respect to the lower atmosphere, it is visible in the optical band only during the solar eclipses as a faint crown (corona in Latin) around the black moon disk. When inspected through spectroscopy the corona reveals unexpected emission lines, which were first identified as due to a new element (coronium) but which were later ascertained to be due to high excitation states of iron. It became then clear that the corona is made of very high temperature gas, hotter than 1 MK(megakelvin). Almost all the gas is fully ionized there and thus interacts effectively with the ambient magnetic field. It is for this reason that the corona appears so inhomogeneous when observed in the X-ray band, in which plasma at million degrees emits most of its radiation. In particular, the plasma is confined inside magnetic flux tubes which are anchored on both sides to the underlying photosphere. When the confined plasma is heated more than the surroundings, its pressure and density increase. Since the tenuous plasma is optically thin, the intensity of its radiation is proportional to the square of the density, and the tube becomes much brighter than the surrounding ones and looks like a bright closed arch: a coronal loop.

Credit: Fabio Reale

The Milky Way above Las Campanas Observatory (LCO)

Image Credit: Tudorica Alexandru

The Milky Way above Las Campanas Observatory (LCO)

Image Credit: Tudorica Alexandru

karaniwangbinatilyo:

FORCES OF NATURE