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)

Henrietta Swan Leavitt

The parallax method used to measure the distances to nearby stars, pioneered by Bessel and others could only be used on stars closer than 100 light years away.  But most stars and other galaxies are far beyond that distance. The key for finding the distance to stars much further away was discovered by Henrietta Swan Leavitt who worked at Harvard College Observatory as a “computer,” one of several women paid 25 to 30 cents per hour to extract data from thousands of photographic plates.

Unfortunately stars are not the same intrinsic brightness (or luminosity), so it is impossible to tell if a star appears dim because it’s far away, or because it doesn’t put out much light. The key for finding the distance to stars was discovered by Henrietta Swan Leavitt who worked at Harvard College Observatory as a “computer,” one of several women paid 25 to 30 cents per hour to take data from thousands of photographic plates.

Leavitt’s assignment was to identify variable stars, which are stars that change in brightness over a few hours, days, or weeks. To do this she would compare two photos of a star field taken a few days or weeks apart. She used an instrument called a blink comparator that flips back and forth quickly between the two images so that a variable star shows up as a flashing spot. With this method she found more than 2,400 variable stars.

Leavitt became curious about whether there might be a relationship between the brightness of a variable star and the length of its period (how long it takes for the star to get brighter, dimmer, then brighter again). That was difficult because she did not know the intrinsic brightness of any given variable. She solved the problem by restricting her search to a particular kind of variable star known as Cepheid variables that reside in the Small Magellanic Cloud—a distant star cluster. She reasoned that all stars in the cluster must be approximately the same distance from Earth.

Her hunch paid off. Leavitt discovered 25 Cepheid variables in the cluster and created a graph showing the maximum brightness of each star and the length of its period. As she suspected, there was a clear relationship. Brighter stars had longer periods. All that was needed to find actual distances was to find the distance to just one nearby Cepheid variable. A few years later a team of astronomers did just that, making it possible to measure the distance to any Cepheid.

Image Credit: Dana Berry/NASA

ri-science:

What is the future of the LHC?

How has the discovery of the Higgs Boson two years ago affected our understanding of particle physics? What changes to the LHC can we expect to see in the future? And why on earth has it been closed for two years? The LHC will restart in 2015 with double the collision energy after its two-year break.

Join us on twitter to ask CERN’s Clara Nellist all your burning questions about life and research at the LHC. She’ll be online from 7pm UK Time (that’s 11am PDT/2pm EDT) on Tuesday 16 September  - follow along and get involved in the conversation by following #RiChat, @claranellist and @Ri_science.

Watch Clara’s intro to her research and the chat:

kqedscience:

The Last Summer ‘Supermoon’ Of 2014 Is Also A Harvest Moon
“Skywatchers, you’re in for a treat. Tonight’s “supermoon” is a pretty special one.
When the moon turns full on Monday, Sept. 8 at 9:38 p.m. EDT, it not only will become the last supermoon of the summer, but also this year’s Harvest Moon — which is a full moon that occurs closest to the autumnal equinox.”
Learn more from the huffingtonpost.

kqedscience:

The Last Summer ‘Supermoon’ Of 2014 Is Also A Harvest Moon

Skywatchers, you’re in for a treat. Tonight’s “supermoon” is a pretty special one.

When the moon turns full on Monday, Sept. 8 at 9:38 p.m. EDT, it not only will become the last supermoon of the summer, but also this year’s Harvest Moon — which is a full moon that occurs closest to the autumnal equinox.”

Learn more from the huffingtonpost.

space-facts:


Pluto is the second closest dwarf planet to the Sun and is also the second most massive dwarf planet. It is possible that either Pluto is the largest dwarf planet but Pluto’s atmosphere makes it is difficult to determine a precise size. Pluto was discovered on February 18th, 1930 by Clyde W. Tombaugh at the Lowell Observatory.

Image credit: NASA, based on the planet profiles by Space Plasma

space-facts:

Pluto is the second closest dwarf planet to the Sun and is also the second most massive dwarf planet. It is possible that either Pluto is the largest dwarf planet but Pluto’s atmosphere makes it is difficult to determine a precise size. Pluto was discovered on February 18th, 1930 by Clyde W. Tombaugh at the Lowell Observatory.

Image credit: NASA, based on the planet profiles by Space Plasma

On August 24th at 12:17 UT, NASA’s Solar Dynamics Observatory recorded this M5.6-category explosion near the eastern limb of the sun.

The source of the blast was sunspot AR2151. As the movie shows, an instability in the suspot’s magnetic canopy hurled a dense plume of plasma into space. If that plasma cloud were to hit Earth, the likely result would be strong geomagnetic storms. However, because of the sunspot’s location near the edge of the solar disk, Earth was not in the line of fire.

Even so, the flare did produce some Earth effects. A pulse of extreme UV radiation from the explosion partially ionized our planet’s upper atmosphere, resulting in a Sudden Ionospheric Disturbance (SID). Waves of ionization altered the normal propagation of VLF (very low frequency) radio transmissions over the the dayside of Earth, an effect recorded at the Polarlightcenter in Lofoten, Norway: data.

Credit: NASA/SDO

s-c-i-guy:

Bill Nye Fights Back
How a mild-mannered children’s celebrity plans to save science in America—or go down swinging.
Read the full article on Popular Science

s-c-i-guy:

Bill Nye Fights Back

How a mild-mannered children’s celebrity plans to save science in America—or go down swinging.

Read the full article on Popular Science

comaniddy:

That creature you see right there is the teeny-tiny Water Bear. They are one of Nature’s toughest creatures.

I found this little tardigrade on tree moss. And in an upcoming SciTune, the folks from the BioBus and I will teach you how to find them!


While sunspots are relatively cool and quiescent regions on the Sun, the photosphere around them sometimes erupts with outflows of high energy particles in active regions. Most often these eruptions are in the form of loops and sheets called prominences which remain under the control of the intense magnetic fields associated with solar storms. There are other events which in a matter of minutes can release enormous amounts of energy and eject material out into space. Such violent events are called solar flares.

Images credit: TRACE/NASA

While sunspots are relatively cool and quiescent regions on the Sun, the photosphere around them sometimes erupts with outflows of high energy particles in active regions. Most often these eruptions are in the form of loops and sheets called prominences which remain under the control of the intense magnetic fields associated with solar storms. There are other events which in a matter of minutes can release enormous amounts of energy and eject material out into space. Such violent events are called solar flares.

Images credit: TRACE/NASA

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

Planets of Our Solar System

Our solar system officially has eight planets and one star: the Sun. The discovery of an object larger than Pluto in 2005 rekindled the debate over whether such objects, belonging to the Kuiper Belt – a collection of icy bodies located beyond Neptune – should be called planets. Pluto and other large members of the Kuiper Belt are now considered “dwarf planets.”

Planet facts: space-facts.com

scinote:

Coming soon: SciNote.org, launched by entrop-e, shychemist, and geogallery, is Tumblr’s project for promoting science education around the world.

At SciNote, we believe that science shouldn’t just be reading about the ideas of people with PhDs and Nobel Prizes. We believe that science is an active process of asking questions and finding answers.
That’s why we, at SciNote, want to hear from you. We want to ponder the interesting questions you pose and get excited with you over the cool science you see in your world.
SciNote will feature the best of the Tumblr science community, and we will compile and publish the top posts from every year in the form of a magazine available both digitally and in print. Think of SciNote magazine as the Tumblr science magazine.
We hope to celebrate our launch by featuring some of the coolest science from around Tumblr. So before we launch SciNote, we would like to collect 25 science posts and/or questions from you, including:
the most interesting science news you have come across
questions you’ve always wanted to ask
fascinating facts that you’ve learned
pictures of nature and/or science that you’ve taken
cool research that you’ve participated in
any other science-related thing you’d like to tell us!

So please:
Submit posts or ask questions to be featured on our blog and for an opportunity to be published in SciNote magazine.
Follow our blog at SciNote.org.
Read more about our project here.
If you’re interested, apply to join our staff here.
Reblog this post so that we can collect 25 posts and launch our project as soon as possible!
Thank you all and happy science!

scinote:

Coming soon: SciNote.org, launched by entrop-e, shychemist, and geogallery, is Tumblr’s project for promoting science education around the world.

At SciNote, we believe that science shouldn’t just be reading about the ideas of people with PhDs and Nobel Prizes. We believe that science is an active process of asking questions and finding answers.

That’s why we, at SciNote, want to hear from you. We want to ponder the interesting questions you pose and get excited with you over the cool science you see in your world.

SciNote will feature the best of the Tumblr science community, and we will compile and publish the top posts from every year in the form of a magazine available both digitally and in print. Think of SciNote magazine as the Tumblr science magazine.

We hope to celebrate our launch by featuring some of the coolest science from around Tumblr. So before we launch SciNote, we would like to collect 25 science posts and/or questions from you, including:

  • the most interesting science news you have come across
  • questions you’ve always wanted to ask
  • fascinating facts that you’ve learned
  • pictures of nature and/or science that you’ve taken
  • cool research that you’ve participated in
  • any other science-related thing you’d like to tell us!

So please:

  1. Submit posts or ask questions to be featured on our blog and for an opportunity to be published in SciNote magazine.
  2. Follow our blog at SciNote.org.
  3. Read more about our project here.
  4. If you’re interested, apply to join our staff here.
  5. Reblog this post so that we can collect 25 posts and launch our project as soon as possible!

Thank you all and happy science!

Our Sun constantly emits plasma which moves out in all directions at very high speeds and fills the entire solar system. The complex interaction between the Sun’s plasma atmosphere and its magnetic field gives rise to a wide range of fascinating and spectacular phenomena. The fluctuation of the sun’s magnetic fields can cause a large portion of the outer atmosphere to expand rapidly, spewing a tremendous amount of particles into space. These large eruptions of magnetized plasma are called coronal mass ejections. CMEs are the most spectacular and potentially harmful manifestations of solar activity. Some of these eruptive events accelerate particles to very high energies, high enough to penetrate a space suit or the hull of a spacecraft and can cause severe disturbances in the geospace environment when they encounter Earth’s magnetic field. However, only about 1% of the CMEs produce strong SEP (solar energetic particles) events. 

Credit: NASA/SDO/Duberstein

txchnologist:

Electric Fields Made Visible

Physics educator James Lincoln helps people understand the natural world. The gifs above are from a Youtube video he made on how to “see” an electric field, the region around a charged object where electric force is experienced. When the object is positively charged, electric field lines extend radially outward from the object. When the object is negatively charged, the lines extend radially inward.  

Click the gifs for more info or see the full video below.

Read More

Propylene on Titan

With a thick atmosphere, clouds, a rain cycle and giant lakes, Saturn’s large moon Titan is a surprisingly Earthlike place. But unlike on Earth, Titan’s surface is far too cold for liquid water - instead, Titan’s clouds, rain, and lakes consist of liquid hydrocarbons like methane and ethane (which exist as gases here on Earth). When these hydrocarbons evaporate and encounter ultraviolet radiation in Titan’s upper atmosphere, some of the molecules are broken apart and reassembled into longer hydrocarbons like ethylene and propane.

NASA’s Voyager 1 spacecraft first revealed the presence of several species of atmospheric hydrocarbons when it flew by Titan in 1980, but one molecule was curiously missing - propylene, the main ingredient in plastic number 5. Now, thanks to NASA’s Cassini spacecraft, scientists have detected propylene on Titan for the first time, solving a long-standing mystery about the solar system’s most Earthlike moon.

NASA PlanetaryScientist Conor Nixon explains his discovery of propylene on Titan, Saturn’s largest moon. Scientists have known about the presence of atmospheric hydrocarbons on Titan since Voyager 1 flew by in 1980, but one molecule, propylene, was curiously missing. Now, thanks to new data from NASA’s Cassini spacecraft, propylene has been detected for the first time on Titan.

Credit: NASA’s Goddard Space Flight Center