Solar System: 10 Things To Know This Week

Tornado Recovery Underway at Michoud Assembly Facility

Teams at our Michoud Assembly Facility in New Orleans worked overnight and are continuing Wednesday with assessment and recovery efforts following a tornado strike at the facility Tuesday at 11:25 a.m. CST. All 3,500 employees at the facility have been accounted for, with five sustaining minor injuries.

Teams worked through the night on temporary repairs to secure the perimeter fencing and provide access for the essential personnel through the main gate. Approximately 40 to 50 percent of the buildings at Michoud have some kind of damage; about five buildings have some form of severe damage.

Approximately 200 parked cars were damaged, and there was damage to roads and other areas near Michoud.

“The entire NASA family pulls together during good times and bad, and the teams at the Michoud Assembly Facility are working diligently to recover from the severe weather that swept through New Orleans Tuesday and damaged the facility,” said acting NASA Administrator Robert Lightfoot. “We are thankful for the safety of all the NASA employees and workers of onsite tenant organizations, and we are inspired by the resilience of Michoud as we continue to assess the facility’s status.”

Teams will reassess the condition of the Vertical Assembly Center (VAC), as the initial examination revealed some electrical damage to its substation. The VAC is used to weld all major pieces of hardware for the core stage of the Space Launch System. The most recently welded part was removed from the facility last week.

The team has prioritized completing the assessment at the site’s main manufacturing building for the Space Launch System and Orion spacecraft flight hardware so power can be restored in phases and temporary protection put in place to shield hardware from any further inclement weather.

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Scary Space Stories to Tell in the Dark

The universe is full of dazzling sights, but there’s an eerie side of space, too. Nestled between the stars, shadowy figures lurk unseen. The entire galaxy could even be considered a graveyard, full of long-dead stars. And it’s not just the Milky Way – the whole universe is a bit like one giant haunted house! Our Nancy Grace Roman Space Telescope will illuminate all kinds of spine-chilling cosmic mysteries when it launches in 2027, but for now settle in for some true, scary space stories.

Flickering Lights

One of the first signs that things are about to get creepy in a scary movie is when the lights start to flicker. That happens all the time in space, too! But instead of being a sinister omen, it can help us find planets circling other stars.

Roman will stare toward the heart of our galaxy and watch to see when pairs of stars appear to align in the sky. When that happens, the nearer star – and orbiting planets – can lens light from the farther star, creating a brief brightening. That’s because every massive object warps the fabric of space-time, changing the path light takes when it passes close by. Roman could find around 1,000 planets using this technique, which is called microlensing.

The mission will also see little flickers when planets cross in front of their host star as they orbit and temporarily dim the light we receive from the star. Roman could find an additional 100,000 planets this way!

Galactic Ghosts

Roman is going to be one of the best ghost hunters in the galaxy! Since microlensing relies on an object’s gravity, not its light, it can find all kinds of invisible specters drifting through the Milky Way. That includes rogue planets, which roam the galaxy alone instead of orbiting a star…

…and solo stellar-mass black holes, which we can usually only find when they have a visible companion, like a star. Astronomers think there should be 100 million of these black holes in our galaxy.

Stellar Skeletons

Black holes aren’t the only dead stars hiding in the sky. When stars that aren’t quite massive enough to form black holes run out of fuel, they blast away their outer layers and become neutron stars. These stellar cores are the densest material we can directly observe. One sugar cube of neutron star material would weigh about 1 billion tons (or 1 trillion kilograms) on Earth! Roman will be able to detect when these extreme objects collide.

Smaller stars like our Sun have less dramatic fates. After they run out of fuel, they swell up and shrug off their outer layers until only a small, hot core called a white dwarf remains. Those outer layers may be recycled into later generations of stars and planets. Roman will explore regions where new stars are bursting to life, possibly containing the remnants of such dead stars.

Cosmic Cobwebs

If we zoom out far enough, the structure of space looks like a giant cobweb! The cosmic web is the large-scale backbone of the universe, made up mainly of a mysterious substance known as dark matter and laced with gas, upon which galaxies are built. Roman will find precise distances for more than 10 million galaxies to map the structure of the cosmos, helping astronomers figure out why the expansion of the universe is speeding up.

Learn more about the exciting science this mission will investigate on Twitter and Facebook.

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Experience High-Res Science in First 8K Footage from Space

Fans of science in space can now experience fast-moving footage in even higher definition as NASA delivers the first 8K ultra high definition (UHD) video of astronauts living, working and conducting research from the International Space Station.

The same engineers who sent high-definition (HD) cameras, 3D cameras, and a camera capable of recording 4K footage to the space station have now delivered a new camera– Helium 8K camera by RED – capable of recording images with four times the resolution than the previous camera offered.

Let’s compare this camera to others: The Helium 8K camera is capable of shooting at resolutions ranging from conventional HDTV up to 8K, specifically 8192 x 4320 pixels. By comparison, the average HD consumer television displays up to 1920 x 1080 pixels of resolution, and digital cinemas typically project 2K to 4K.

Viewers can watch as crew members advance DNA sequencing in space with the BEST investigation, study dynamic forces between sediment particles with BCAT-CS, learn about genetic differences in space-grown and Earth-grown plants with Plant Habitat-1, observe low-speed water jets to improve combustion processes within engines with Atomization and explore station facilities such as the MELFI, the Plant Habitat, the Life Support Rack, the JEM Airlock and the CanadArm2.

Delivered to the station aboard the fourteenth SpaceX cargo resupply mission through a Space Act Agreement between NASA and RED, this camera’s ability to record twice the pixels and at resolutions four times higher than the 4K camera brings science in orbit into the homes, laboratories and classrooms of everyone on Earth. 

While the 8K resolutions are optimal for showing on movie screens, NASA video editors are working on space station footage for public viewing on YouTube. Viewers will be able to watch high-resolution footage from inside and outside the orbiting laboratory right on their computer screens. Viewers will need a screen capable of displaying 8K resolution for the full effect, but the imagery still trumps that of standard cameras. RED videos and pictures are shot at a higher fidelity and then down-converted, meaning much more information is captured in the images, which results in higher-quality playback, even if viewers don't have an 8K screen.   

The full UHD files are available for download for use in broadcast. Read the NASA media usage guidelines. 

Magnetospheres: How Do They Work?

The sun, Earth, and many other planets are surrounded by giant magnetic bubbles.

Space may seem empty, but it’s actually a dynamic place, dominated by invisible forces, including those created by magnetic fields.  Magnetospheres – the areas around planets and stars dominated by their magnetic fields – are found throughout our solar system. They deflect high-energy, charged particles called cosmic rays that are mostly spewed out by the sun, but can also come from interstellar space. Along with atmospheres, they help protect the planets’ surfaces from this harmful radiation.

It’s possible that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, so finding magnetospheres around other planets is a big step toward determining if they could support life.

But not all magnetospheres are created equal – even in our own backyard, not all planets in our solar system have a magnetic field, and the ones we have observed are all surprisingly different.

Earth’s magnetosphere is created by the constantly moving molten metal inside Earth. This invisible “force field” around our planet has an ice cream cone-like shape, with a rounded front and a long, trailing tail that faces away from the sun. The magnetosphere is shaped that way because of the constant pressure from the solar wind and magnetic fields on the sun-facing side.

Earth’s magnetosphere deflects most charged particles away from our planet – but some do become trapped in the magnetic field and create auroras when they rain down into the atmosphere.

We have several missions that study Earth’s magnetosphere – including the Magnetospheric Multiscale mission, Van Allen Probes, and Time History of Events and Macroscale Interactions during Substorms (also known as THEMIS) – along with a host of other satellites that study other aspects of the sun-Earth connection.

Mercury, with a substantial iron-rich core, has a magnetic field that is only about 1% as strong as Earth’s. It is thought that the planet’s magnetosphere is stifled by the intense solar wind, limiting its strength, although even without this effect, it still would not be as strong as Earth’s. The MESSENGER satellite orbited Mercury from 2011 to 2015, helping us understand our tiny terrestrial neighbor.

After the sun, Jupiter has by far the biggest magnetosphere in our solar system – it stretches about 12 million miles from east to west, almost 15 times the width of the sun. (Earth’s, on the other hand, could easily fit inside the sun.) Jupiter does not have a molten metal core like Earth; instead, its magnetic field is created by a core of compressed liquid metallic hydrogen.

One of Jupiter’s moons, Io, has intense volcanic activity that spews particles into Jupiter’s magnetosphere. These particles create intense radiation belts and the large auroras around Jupiter’s poles.

Ganymede, Jupiter’s largest moon, also has its own magnetic field and magnetosphere – making it the only moon with one. Its weak field, nestled in Jupiter’s enormous shell, scarcely ruffles the planet’s magnetic field.

Our Juno mission orbits inside the Jovian magnetosphere sending back observations so we can better understand this region. Previous observations have been received from Pioneers 10 and 11, Voyagers 1 and 2, Ulysses, Galileo and Cassini in their flybys and orbits around Jupiter.

Saturn’s moon Enceladus transforms the shape of its magnetosphere. Active geysers on the moon’s south pole eject oxygen and water molecules into the space around the planet. These particles, much like Io’s volcanic emissions at Jupiter, generate the auroras around the planet’s poles. Our Cassini mission studies Saturn’s magnetic field and auroras, as well as its moon Enceladus.

Uranus’ magnetosphere wasn't discovered until 1986 when data from Voyager 2’s flyby revealed weak, variable radio emissions. Uranus’ magnetic field and rotation axis are out of alignment by 59 degrees, unlike Earth’s, whose magnetic field and rotation axis differ by only 11 degrees. On top of that, the magnetic field axis does not go through the center of the planet, so the strength of the magnetic field varies dramatically across the surface. This misalignment also means that Uranus’ magnetotail – the part of the magnetosphere that trails away from the sun – is twisted into a long corkscrew.

Neptune’s magnetosphere is also tilted from its rotation axis, but only by 47. Just like on Uranus, Neptune’s magnetic field strength varies across the planet. This also means that auroras can be seen away from the planet’s poles – not just at high latitudes, like on Earth, Jupiter and Saturn.

Does Every Planet Have a Magnetosphere?

Neither Venus nor Mars have global magnetic fields, although the interaction of the solar wind with their atmospheres does produce what scientists call an “induced magnetosphere.” Around these planets, the atmosphere deflects the solar wind particles, causing the solar wind’s magnetic field to wrap around the planet in a shape similar to Earth’s magnetosphere.

What About Beyond Our Solar System?

Outside of our solar system, auroras, which indicate the presence of a magnetosphere, have been spotted on brown dwarfs – objects that are bigger than planets but smaller than stars.

There’s also evidence to suggest that some giant exoplanets have magnetospheres. As scientists now believe that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, finding magnetospheres around exoplanets is a big step in finding habitable worlds.  

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Where in the World is Our Flying Telescope? New Zealand!

Our flying observatory SOFIA carries a telescope inside this Boeing 747SP aircraft. Scientists use SOFIA to study the universe — including stars, planets and black holes — while flying as high as 45,000 feet.

SOFIA is typically based at our Armstrong Flight Research Center in Palmdale, California, but recently arrived in Christchurch, New Zealand, to study celestial objects that are best observed from the Southern Hemisphere.

So what will we study from the land down under?

Eta Carinae

Eta Carinae, in the southern constellation Carina, is the most luminous stellar system within 10,000 light-years of Earth. It’s made of two massive stars that are shrouded in dust and gas from its previous eruptions and may one day explode as a supernova. We will analyze the dust and gas around it to learn how this violent system evolves.

Celestial Magnetic Fields

We can study magnetic fields in the center of our Milky Way galaxy from New Zealand because there the galaxy is high in the sky — where we can observe it for long periods of time. We know that this area has strong magnetic fields that affect the material spiraling into the black hole here and forming new stars. But we want to learn about their shape and strength to understand how magnetic fields affect the processes in our galactic center.

Saturn’s Moon Titan

Titan is Saturn’s largest moon and is the only moon in our solar system to have a thick atmosphere — it’s filled with a smog-like haze. It also has seasons, each lasting about seven Earth years. We want to learn if its atmosphere changes seasonally.

Titan will pass in front of a star in an eclipse-like event called an occultation. We’ll chase down the shadow it casts on Earth’s surface, and fly our airborne telescope directly in its center. 

From there, we can determine the temperature, pressure and density of Titan’s atmosphere. Now that our Cassini Spacecraft has ended its mission, the only way we can continue to monitor its atmosphere is by studying these occultation events.

Nearby Galaxies

The Large Magellanic Cloud is a galaxy near our own, but it’s only visible from the Southern Hemisphere! Inside of it are areas filled with newly forming stars and the leftovers from a supernova explosion.

The Tarantula Nebula

The Tarantula Nebula, also called 30 Doradus, is located in the Large Magellanic Cloud and shown here in this image from Chandra, Hubble and Spitzer. It holds a cluster of thousands of stars forming simultaneously. Once the stars are born, their light and winds push out the material leftover from their parent clouds — potentially leaving nothing behind to create more new stars. We want to know if the material is still expanding and forming new stars, or if the star-formation process has stopped. So our team on SOFIA will make a map showing the speed and direction of the gas in the nebula to determine what’s happening inside it.

Supernova 1987A

Also in the Large Magellanic Cloud is Supernova 1987A, the closest supernova explosion witnessed in almost 400 years. We will continue studying this supernova to better understand the material expanding out from it, which may become the building blocks of future stars and planets. Many of our telescopes have studied Supernova 1987A, including the Hubble Space Telescope and the Chandra X-ray Observatory, but our instruments on SOFIA are the only tools we can use to study the debris around it with infrared light, which let us better understand characteristics of the dust that cannot be measured using other wavelengths of light.

For live updates about our New Zealand observations follow SOFIA on Facebook, Twitter and Instagram.

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The 2017 Atlantic Hurricane Season: What We Learned

The 2017 Atlantic hurricane season was among the top ten most active seasons in recorded history. Our experts are exploring what made this year particularly active and the science behind some of the biggest storms to date.

After a period of 12 years without a Category 3 or higher hurricane making landfall in the U.S., Hurricane Harvey made landfall over Texas as a Category 4 hurricane this August.

Harvey was also the biggest rainfall event ever to hit the continental U.S. with estimates more than 49 inches of rain.

Data like this from our Global Precipitation Measurement Mission, which shows the amount of rainfall from the storm and temperatures within the story, are helping scientists better understand how storms develop. 

The unique vantage point of satellites can also help first responders, and this year satellite data helped organizations map out response strategies during hurricanes Harvey, Irma and Maria. 
 

In addition to satellites, we use ground stations and aircraft to track hurricanes.

We also use the capabilities of satellites like Suomi NPP and others that are able to take nighttime views. In this instance, we were able to view the power outages in Puerto Rico. This allowed first responders to see where the location of impacted urban areas.

The combined effort between us, NOAA, FEMA and other federal agencies helps us understand more about how major storms develop, how they gain strength and how they affect us. 

To learn more about how we study storms, go to www.nasa.gov/Hurricanes.

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Astronaut Journal Entry - Pre-Launch

Currently, six humans are living and working on the International Space Station, which orbits 250 miles above our planet at 17,500mph. Below you will find a real journal entry written by NASA astronaut Scott Tingle.

To read more entires from this series, visit our Space Blogs on Tumblr.

Our crew just finished the final training event before the launch. Tomorrow, at 13:20 local time (Baikonur), we will strap the Soyuz MS-07 spacecraft to our backs and fly it to low Earth orbit. We will spend 2.5 days in low Earth orbit before docking to the MRM-1 docking port on the International Space Station (ISS). There we will begin approximately 168 days of maintenance, service and science aboard one of the greatest engineering marvels that humans have ever created.

Today was bittersweet. Ending a 2-year process of intense training was welcomed by all of us. We are very tired. Seeing our families for the last time was difficult. I am pretty lucky, though. My wife, Raynette, and the kids have grown up around military service and are conditioned to endure the time spent apart during extended calls-to-duty. We are also very much anticipating the good times we will have upon my return in June. Sean and Amy showed me a few videos of them mucking it up at Red Square before flying out to Baikonur. Eric was impressed with the Russian guards marching in to relieve the watch at Red Square. Raynette was taking it all in stride and did not seem surprised by any of it. I think I might have a family of mutants who are comfortable anywhere. Nice! And, by the way, I am VERY proud of all of them!

Tomorrow’s schedule includes a wake-up at 04:00, followed by an immediate medical exam and light breakfast. Upon returning to our quarters, we will undergo a few simple medical procedures that should help make the 2.5-day journey to ISS a little more comfortable. I’ve begun prepping with motion sickness medication that should limit the nausea associated with the first phases of spaceflight. I will continue this effort through docking. This being my first flight, I’m not sure how my body will respond and am taking all precautions to maintain a good working capability. The commander will need my help operating the vehicle, and I need to not be puking into a bag during the busy times. We suit up at 09:30 and then report to the State Commission as “Готовы к Полёту”, or “Ready for Flight”. We’ll enter the bus, wave goodbye to our friends and family, and then head out to the launch pad. Approximately 2 kilometers from the launch pad, the bus will stop. 

The crew will get out, pee on the bus’s tire, and then complete the last part of the drive to the launch pad. This is a traditional event first done by Yuri Gagarin during his historic first flight and repeated in his honor to this day. We will then strap in and prepare the systems for launch. Next is a waiting game of approximately 2 hours. Ouch. The crew provided five songs each to help pass the time. My playlist included “Born to Run” (Springsteen), “Sweet Child O’ Mine” (Guns and Roses), “Cliffs of Dover” (Eric Johnson), “More than a Feeling” (Boston), and “Touch the Sky” (Rainbow Bridge, Russian). Launch will happen precisely at 13:20.

I think this sets the stage. It’s 21:30, only 6.5 hours until duty calls. Time to get some sleep. If I could only lower my level of excitement!

Find more ‘Captain’s Log’ entries HERE.

Follow NASA astronaut Scott Tingle on Instagram and Twitter.

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Solar System: 10 Things to Know This Week

January 8: Images for Your Computer or Phone Wallpaper

Need some fresh perspective? Here are 10 vision-stretching images for your computer desktop or phone wallpaper. These are all real pictures, sent recently by our planetary missions throughout the solar system. You'll find more of our images at solarsystem.nasa.gov/galleries, images.nasa.gov and www.jpl.nasa.gov/spaceimages.

Applying Wallpaper: 1. Click on the screen resolution you would like to use. 2. Right-click on the image (control-click on a Mac) and select the option 'Set the Background' or 'Set as Wallpaper' (or similar).

1. The Fault in Our Mars

This image from our Mars Reconnaissance Orbiter (MRO) of northern Meridiani Planum shows faults that have disrupted layered deposits. Some of the faults produced a clean break along the layers, displacing and offsetting individual beds.

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2. Jupiter Blues

Our Juno spacecraft captured this image when the spacecraft was only 11,747 miles (18,906 kilometers) from the tops of Jupiter's clouds -- that's roughly as far as the distance between New York City and Perth, Australia. The color-enhanced image, which captures a cloud system in Jupiter's northern hemisphere, was taken on Oct. 24, 2017, when Juno was at a latitude of 57.57 degrees (nearly three-fifths of the way from Jupiter's equator to its north pole) and performing its ninth close flyby of the gas giant planet.

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3. A Farewell to Saturn

After more than 13 years at Saturn, and with its fate sealed, our Cassini spacecraft bid farewell to the Saturnian system by firing the shutters of its wide-angle camera and capturing this last, full mosaic of Saturn and its rings two days before the spacecraft's dramatic plunge into the planet's atmosphere on Sept. 15, 2017.

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4. All Aglow

Saturn's moon Enceladus drifts before the rings, which glow brightly in the sunlight. Beneath its icy exterior shell, Enceladus hides a global ocean of liquid water. Just visible at the moon's south pole (at bottom here) is the plume of water ice particles and other material that constantly spews from that ocean via fractures in the ice. The bright speck to the right of Enceladus is a distant star. This image was taken in visible light with the Cassini spacecraft narrow-angle camera on Nov. 6, 2011.

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5. Rare Encircling Filament

Our Solar Dynamics Observatory came across an oddity this week that the spacecraft has rarely observed before: a dark filament encircling an active region (Oct. 29-31, 2017). Solar filaments are clouds of charged particles that float above the Sun, tethered to it by magnetic forces. They are usually elongated and uneven strands. Only a handful of times before have we seen one shaped like a circle. (The black area to the left of the brighter active region is a coronal hole, a magnetically open region of the Sun).

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6. Jupiter's Stunning Southern Hemisphere

See Jupiter's southern hemisphere in beautiful detail in this image taken by our Juno spacecraft. The color-enhanced view captures one of the white ovals in the "String of Pearls," one of eight massive rotating storms at 40 degrees south latitude on the gas giant planet. The image was taken on Oct. 24, 2017, as Juno performed its ninth close flyby of Jupiter. At the time the image was taken, the spacecraft was 20,577 miles (33,115 kilometers) from the tops of the clouds of the planet.

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7. Saturn's Rings: View from Beneath

Our Cassini spacecraft obtained this panoramic view of Saturn's rings on Sept. 9, 2017, just minutes after it passed through the ring plane. The view looks upward at the southern face of the rings from a vantage point above Saturn's southern hemisphere.

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8. From Hot to Hottest

This sequence of images from our Solar Dynamics Observatory shows the Sun from its surface to its upper atmosphere all taken at about the same time (Oct. 27, 2017). The first shows the surface of the sun in filtered white light; the other seven images were taken in different wavelengths of extreme ultraviolet light. Note that each wavelength reveals somewhat different features. They are shown in order of temperature, from the first one at about 11,000 degrees Fahrenheit (6,000 degrees Celsius) on the surface, out to about 10 million degrees in the upper atmosphere. Yes, the sun's outer atmosphere is much, much hotter than the surface. Scientists are getting closer to solving the processes that generate this phenomenon.

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9. High Resolution View of Ceres

This orthographic projection shows dwarf planet Ceres as seen by our Dawn spacecraft. The projection is centered on Occator Crater, home to the brightest area on Ceres. Occator is centered at 20 degrees north latitude, 239 degrees east longitude.

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10. In the Chasm

This image from our Mars Reconnaissance Orbiter shows a small portion of the floor of Coprates Chasma, a large trough within the Valles Marineris system of canyons. Although the exact sequence of events that formed Coprates Chasma is unknown, the ripples, mesas, and craters visible throughout the terrain point to a complex history involving multiple mechanisms of erosion and deposition. The main trough of Coprates Chasma ranges from 37 miles (60 kilometers) to 62 miles (100 kilometers) in width.

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Explore and learn more about our solar system at: solarsystem.nasa.gov/. 

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A Wrinkle in Space-Time: The Eclipse That “Proved” Einstein Right

One hundred years ago a total solar eclipse turned an obscure scientist into a household name. You might have heard of him — his name is Albert Einstein. But how did a solar eclipse propel him to fame?

First, it would be good to know a couple things about general relativity. (Wait, don’t go! We’ll keep this to the basics!)

A decade before he finished general relativity, Einstein published his special theory of relativity, which demonstrates how space and time are interwoven as a single structure he dubbed “space-time.” General relativity extended the foundation of special relativity to include gravity. Einstein realized that gravitational fields can be understood as bends and curves in space-time that affect the motions of objects including stars, planets — and even light.

For everyday situations the centuries-old description of gravity by Isaac Newton does just fine. However, general relativity must be accounted for when we study places with strong gravity, like black holes or neutron stars, or when we need very precise measurements, like pinpointing a position on Earth to within a few feet. That makes it hard to test!

A prediction of general relativity is that light passing by an object feels a slight "tug", causing the light's path to bend slightly. The more mass the object has, the more the light will be deflected. This sets up one of the tests that Einstein suggested — measuring how starlight bends around the Sun, the strongest source of gravity in our neighborhood. Starlight that passes near the edge of the Sun on its way to Earth is deflected, altering by a small amount where those stars appear to be. How much? By about the width of a dime if you saw it at a mile and a quarter away! But how can you observe faint stars near the brilliant Sun? During a total solar eclipse!

That’s where the May 29, 1919, total solar eclipse comes in. Two teams were dispatched to locations in the path of totality — the places on Earth where the Moon will appear to completely cover the face of the Sun during an eclipse. One team went to South America and another to Africa.

On eclipse day, the sky vexed both teams, with rain in Africa and clouds in South America. The teams had only mere minutes of totality during which to take their photographs, or they would lose the opportunity until the next total solar eclipse in 1921! However, the weather cleared at both sites long enough for the teams to take images of the stars during totality.

The teams took two sets of photographs of the same patch of sky – one set during the eclipse and another set a few months before or after, when the Sun was out of the way. By comparing these two sets of photographs, researchers could see if the apparent star positions changed as predicted by Einstein. This is shown with the effect exaggerated in the image above.

A few months after the eclipse, when the teams sorted out their measurements, the results demonstrated that general relativity correctly predicted the positions of the stars. Newspapers across the globe announced that the controversial theory was proven (even though that’s not quite how science works). It was this success that propelled Einstein into the public eye.

The solar eclipse wasn’t the first test of general relativity. For more than two centuries, astronomers had known that Mercury’s orbit was a little off. Its perihelion — the point during its orbit when it is closest to the Sun — was changing faster than Newton’s laws predicted. General relativity easily explains it, though, because Mercury is so close to the Sun that its orbit is affected by the Sun’s dent in space-time, causing the discrepancy.  

In fact, we still test general relativity today under different conditions and in different situations to see whether or not it holds up. So far, it has passed every test we’ve thrown at it.

Curious to know where we need general relativity to understand objects in space? Tune into our Tumblr tomorrow to find out!

You can also read more about how our understanding of the universe has changed during the past 100 years, from Einstein's formulation of gravity through the discovery of dark energy in our Cosmic Times newspaper series.

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Solar System 10 Things to Know: Planetary Atmospheres

Every time you take a breath of fresh air, it’s easy to forget you can safely do so because of Earth’s atmosphere. Life on Earth could not exist without that protective cover that keeps us warm, allows us to breathe and protects us from harmful radiation—among other things.

What makes Earth’s atmosphere special, and how do other planets’ atmospheres compare? Here are 10 tidbits:

1. On Earth, we live in the troposphere, the closest atmospheric layer to Earth’s surface. “Tropos” means “change,” and the name reflects our constantly changing weather and mixture of gases. 

It’s 5 to 9 miles (8 to 14 kilometers) thick, depending on where you are on Earth, and it’s the densest layer of atmosphere. When we breathe, we’re taking in an air mixture of about 78 percent nitrogen, 21 percent oxygen and 1 percent argon, water vapor and carbon dioxide. More on Earth’s atmosphere›

2. Mars has a very thin atmosphere, nearly all carbon dioxide. Because of the Red Planet’s low atmospheric pressure, and with little methane or water vapor to reinforce the weak greenhouse effect (warming that results when the atmosphere traps heat radiating from the planet toward space), Mars’ surface remains quite cold, the average surface temperature being about -82 degrees Fahrenheit (minus 63 degrees Celsius). More on the greenhouse effect›

3. Venus’ atmosphere, like Mars’, is nearly all carbon dioxide. However, Venus has about 154,000 times more carbon dioxide in its atmosphere than Earth (and about 19,000 times more than Mars does), producing a runaway greenhouse effect and a surface temperature hot enough to melt lead. A runaway greenhouse effect is when a planet’s atmosphere and surface temperature keep increasing until the surface gets so hot that its oceans boil away. More on the greenhouse effect›

4. Jupiter likely has three distinct cloud layers (composed of ammonia, ammonium hydrosulfide and water) in its "skies" that, taken together, span an altitude range of about 44 miles (71 kilometers). The planet's fast rotation—spinning once every 10 hours—creates strong jet streams, separating its clouds into dark belts and bright zones wrapping around the circumference of the planet. More on Jupiter›

5. Saturn’s atmosphere—where our Cassini spacecraft ended its 13 extraordinary years of exploration of the planet—has a few unusual features. Its winds are among the fastest in the solar system, reaching speeds of 1,118 miles (1,800 kilometers) per hour. Saturn may be the only planet in our solar system with a warm polar vortex (a mass of swirling atmospheric gas around the pole) at both the North and South poles. Also, the vortices have “eye-wall clouds,” making them hurricane-like systems like those on Earth.

Another uniquely striking feature is a hexagon-shaped jet streamencircling the North Pole. In addition, about every 20 to 30 Earth years, Saturn hosts a megastorm (a great storm that can last many months). More on Saturn›

6. Uranus gets its signature blue-green color from the cold methane gas in its atmosphere and a lack of high clouds. The planet’s minimum troposphere temperature is 49 Kelvin (minus 224.2 degrees Celsius), making it even colder than Neptune in some places. Its winds move backward at the equator, blowing against the planet’s rotation. Closer to the poles, winds shift forward and flow with the planet’s rotation. More on Uranus›

7. Neptune is the windiest planet in our solar system. Despite its great distance and low energy input from the Sun, wind speeds at Neptune surpass 1,200 miles per hour (2,000 kilometers per hour), making them three times stronger than Jupiter’s and nine times stronger than Earth’s. Even Earth's most powerful winds hit only about 250 miles per hour (400 kilometers per hour). Also, Neptune’s atmosphere is blue for the very same reasons as Uranus’ atmosphere. More on Neptune›

8. WASP-39b, a hot, bloated, Saturn-like exoplanet (planet outside of our solar system) some 700 light-years away, apparently has a lot of water in its atmosphere. In fact, scientists estimate that it has about three times as much water as Saturn does. More on this exoplanet›

9. A weather forecast on “hot Jupiters”—blistering, Jupiter-like exoplanets that orbit very close to their stars—might mention cloudy nights and sunny days, with highs of 2,400 degrees Fahrenheit (about 1,300 degrees Celsius, or 1,600 Kelvin). Their cloud composition depends on their temperature, and studies suggest that the clouds are unevenly distributed. More on these exoplanets›

10. 55 Cancri e, a “super Earth” exoplanet (a planet outside of our solar system with a diameter between Earth’s and Neptune’s) that may be covered in lava, likely has an atmosphere containing nitrogen, water and even oxygen–molecules found in our atmosphere–but with much higher temperatures throughout. Orbiting so close to its host star, the planet could not maintain liquid water and likely would not be able to support life. More on this exoplanet›

Read the full version of this week’s Solar System 10 Things to Know HERE.

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