Why is Everything Spherical?

Why is Everything Spherical?

Have you ever noticed that everything in space is a sphere? The Sun, the Earth, the Moon and the other planets and their moons… all spheres. Except for the stuff which isn’t spheres. What’s going on?

Have you noticed that a good portion of things in space are shaped like a sphere? Stars, planets, and moons are all spherical.

Why? It all comes down to gravity. All the atoms in an object pull towards a common center of gravity, and they’re resisted outwards by whatever force is holding them apart. The final result could be a sphere… but not always, as we’re about to learn.

Consider a glass of water. If you could see the individual molecules jostling around, you’d see them trying to fit in as snugly as they can, tension making the top of the water smooth and even.

Imagine a planet made entirely of water. If there were no winds, it would be perfectly smooth. The water molecules on the north pole are pulling towards the molecules on the south pole. The ones on the left are pulling towards the right. With all points pulling towards the center of the mass you would get a perfect sphere.

Gravity and surface tension pull it in, and molecular forces are pushing it outward. If you could hold this massive water droplet in an environment where it would remain undisturbed, eventually the water would reach a perfect balance. This is known as “hydrostatic equilibrium”.

Stars, planets and moons can be made of gas, ice or rock. Get enough mass in one area, and it’s going to pull all that stuff into a roughly spherical shape. Less massive objects, such as asteroids, comets, and smaller moons have less gravity, so they may not pull into perfect spheres.

UT Jupiter Oval BA Chris Go
Jupiter Credit: Christopher Go

As you know, most of the celestial bodies we’ve mentioned rotate on an axis, and guess what, those ones aren’t actually spheres either. The rapid rotation flattens out the middle, and makes them wider across the equator than from pole to pole. Earth is perfect example of this, and we call its shape an oblate spheroid.

Jupiter is even more flattened because it spins more rapidly. A day on Jupiter is a short 9.9 hours long. Which leaves it a distorted imperfect sphere at 71,500 km across the equator and just 66,900 from pole to pole.

Stars are similar. Our Sun rotates slowly, so it’s almost a perfect sphere, but there are stars out there that spin very, very quickly. VFTS 102, a giant star in the Tarantula nebula is spinning 100 times faster than the Sun. Any faster and it would tear itself apart from centripetal forces.

This oblate spheroid shape helps indicate why there are lots of flattened disks out there. This rapid spinning, where centripetal forces overcome gravitational attraction that creates this shape. You can see it in black hole accretion disks, solar systems, and galaxies.

Objects tend to form into spheres. If they’re massive enough, they’ll overcome the forces preventing it. But… if they’re spinning rapidly enough, they’ll flatten out all the way into disks.

The Place Where Earth from Space Looks Like a Floating Piece of Cardboard

An image taken from the International Space Station taken on Jun 23, 2014 showing Western Sahara , near El Aaiun. Credit: Reid Wiseman/NASA.

As we’ve noted before, astronaut Reid Wiseman is sending out a bevy of tweets and pictures from his perch on board the International Space Station, but this recent image got our attention.

“Can’t explain it, just looked oddly unnatural to me and I liked it,” Wiseman said on Twitter, leaving no info on what Earthly feature might be.

Floating cardboard? That’s what many people thought. Comments from Twitter:

So what is this image and where on Earth is it?

I checked with Peter Caltner, who regularly tweets information on astronaut photos and he said the image shows Western Sahara, near El Aaiun (coordinates 26.824071,-13.222504) and the straight white line is a conveyor belt facility from a phosphate mine at Bou Craa that goes to a loading port at the coast. The conveyer belt is about 60 miles/100 km long, Peter noted.

You can see more images of this feature in this Google search, but none of them have quite the angle Wiseman had, which gave it the straight-edge box-like appearance from space.

See more comments about the image here.

Thanks again to Peter Caltner for his assistance!

Watch the Rise and Fall of a Towering Inferno on the Sun

A solar prominence imaged on May 27, 2014. Earth and Moon are shown to scale at the bottom. (NASA/SDO)

Caught on camera by NASA’s Solar Dynamics Observatory, a prominence blazes hundreds of thousands of miles out from the Sun’s surface (i.e., photosphere) on May 27, 2014. The image above, seen in extreme ultraviolet wavelengths, shows a brief snapshot of the event with the column of solar plasma stretching nearly as far as the distance between Earth and the Moon.

Watch a video of the event below:

The video covers a span of about two hours.

Although it might look fiery in these images, a prominence isn’t flame — it’s powered by rising magnetic fields trapping and carrying the Sun’s superheated material up into the corona. And while this may not have been a unique or unusual event — or even particularly long-lived — it’s still an impressive reminder of the immense scale and energy of our home star!

Credit: NASA/SDO

Why is the Moon Leaving Us?

Why is the Moon Leaving Us?

Goodbye Moon. Every year, the Moon slips a few centimeters away from us, slowing down our day. Why is the Moon drifting away from us, and how long will it take before the Earth and the Moon are tidally locked to each other?

We had a good run, us and the Moon. Grab your special edition NASA space tissues because today we’re embarking on a tale of orbital companionship, childhood sweethearts and heartache.

You could say we came from the same part of town. A long time ago the Mars-sized object Theia, collided with the Earth and the Moon was formed out of the debris from the collision.

We grew up together. Counting from the very beginning, this relationship has lasted for 4.5 billion years. We had some good times. Some bad times. Gravitationally linked, arm in arm, inside our solar family sedan traversing the galaxy.

But now, tragedy. The Moon, OUR Moon, is moving on to brighter horizons. We used to be much closer when we were younger and time seemed to fly by much faster. In fact, 620 million years ago, a day was only 21 hours long. Now they’ve dragged out to 24 hours and they’re just getting longer, and the Moon is already at a average distance of 384,400 km. It almost feels too far away.

If we think back far enough to when we were kids, there was a time when a day was just 2 – 3 hours long, and the Moon was much closer. It seemed like we did everything together back then. But just like people, massive hunks of rock and materials flying through space change, and their relationships change as well.

Our therapist told us it wasn’t a good idea to get caught up on minutiae, but we’ve done some sciencing using the retroreflector experiments placed by Apollo astronauts, and it looks as though the Moon has always had one foot out the door.

Today it’s drifting away at 1-2 cm/year. Such heartache! We just thought it seemed like the days were longer, but it’s not just an emotional effect of seeing our longtime friend leaving us, there’s a real physical change happening. Our days are getting 1/500th of a second longer every century.

I can’t help but blame myself. If only we knew why. Did the Moon find someone new? Someone more attractive? Was it that trollop Venus, the hottest planet in the whole solar system? It’s really just a natural progression. It’s nature. It’s gravity and tidal forces.

And no, that’s not a metaphor. The Earth and the Moon pull at each other with their gravity. Their shapes get distorted and the pull of this tidal force creates a bulge. The Earth has a bulge facing towards the Moon, and the Moon has a more significant bulge towards the Earth.

A series of photos combined to show the rise of the July 22, 2013 ‘super’ full moon over the Rocky Mountains, shot near Vail, Colorado, at 10,000ft above sea level in the White River National Forest. Moon images are approximately 200 seconds apart. Credit and copyright: Cory Schmitz
A series of photos combined to show the rise of the July 22, 2013 ‘super’ full moon over the Rocky Mountains, shot near Vail, Colorado, at 10,000ft above sea level in the White River National Forest. Moon images are approximately 200 seconds apart. Credit and copyright: Cory Schmitz

These bulges act like handles for gravity, which slows down their rotation. The process allowed the Earth’s gravity to slow the Moon to a stop billions of years ago. The Moon is still working on the Earth to change its ways, but it’ll be a long time before we become tidally locked to the Moon.

This slowing rotation means energy is lost by the Earth. This energy is transferred to the Moon which is speeding up, and as we’ve talked about in previous episodes the faster something orbits, the further and further it’s becomes from the object it’s orbiting.

Will it ever end? We’re so attached, it seems like it’ll take forever to figure out who’s stuff belongs to who and who gets the dog. Fear not, there is an end in sight. 50 billion years from now, 45 billion years after the Sun has grown weary of our shenanigans and become a red giant, when the days have slowed to be 45 hours long, the Moon will consider itself all moved into its brand new apartment ready to start its new life.

What about the neighbors down the street? How are the other orbital relationships faring. I know there’s a lot of poly-moon-amory taking place out there in the Solar System. We’re not the only ones with Moons tidally locked. There’s Phobos and Deimos to Mars, many of the moons of Jupiter and Saturn are, and Pluto and Charon are even tidally locked to each other, forever. Now’s that’s real commitment. So, in the end. The lesson here is people and planets change. The Moon just needs its space, but it still wants to be friends.

What do you think? If you were writing a space opera about the Earth and the Moon break-up, what was it that finally came between them? Tell us in the comments below.

Stunning Snapshots from Space Courtesy of Reid Wiseman

Sunset-lit clouds swirl over Perth on May 31, 2014 (Reid Wiseman/NASA)

On May 28 the crew of Expedition 40/41 launched from Baikonur Cosmodrome, their Soyuz TMA-13M arriving at the International Space Station about eight and a half hours later. And it didn’t take much time for the newly-arrived NASA astronaut Reid Wiseman to start taking photos from his new vantage point in orbit and sharing them on Twitter for the rest of us to enjoy! Here are some of Reid’s latest images from the edge of space, looking down on the beautiful blue world we call home.

One of Reid Wiseman's first few tweets from space
One of Reid Wiseman’s first few tweets from space!
A "beautiful pass over the Falkland Islands" (aka Malvinas) on May 30 with docked Soyuz in the foreground
A “beautiful pass over the Falkland Islands” (aka Islas Malvinas) on May 30 with docked Soyuz in the foreground
Reid confirmed that the Earth is indeed round with a 12mm lens on June 1
Reid confirmed that the Earth is indeed round with a 12mm lens on June 1
Looking down on glacial flows near the Strait of Magellan
Looking down on glacial flows near the Strait of Magellan
Pink clouds at sunset may look beautiful from Earth but "not as pretty here" according to Reid Wiseman
Pink clouds at sunset may look beautiful from Earth but “not as pretty here” according to Reid Wiseman
May 31 was a "nice day to hit the beach" in Santos, Brazil
May 31 was a “nice day to hit the beach” in Santos, Brazil
"Our planet is almost all ocean and so pretty," Tweeted Reid on June 1
“Our planet is almost all ocean and so pretty,” Tweeted Reid on June 1
A "Soyuz selfie" in the cupola with Expedition 40/41 crew members Alexander Gerst, Oleg Artemyev, and Reid Wiseman, shared on June 2
A “Soyuz group selfie” in the cupola with Expedition 40/41 crew members Alexander Gerst, Oleg Artemyev, and Reid Wiseman, shared on June 2
"Chile just left me speechless," Reid tweeted on June 4
“Chile just left me speechless,” Reid tweeted on June 4
"Clouds turn 2D into 3D" tweeted Reid on Thursday, June 5
“Clouds turn 2D into 3D” tweeted Reid on Thursday, June 5
Just a week into his stay aboard the ISS microgravity is already second nature!
Just a week into his stay aboard the ISS microgravity is already second nature!

See these photos (and more as they are taken!) on Reid Wiseman’s Twitter feed, and learn more about Expedition 40 here.

Photos courtesy Reid Wiseman/NASA.

Selfies from Around the World Combine to Make a Portrait of Earth

Images of Earth assembled from over 36,000 fan-submitted "selfless" on Earth Day, April 22, 2014 (NASA)

On Earth Day, April 22, NASA invited people around the world to share their “selfies” on social media sites like Twitter, Facebook, Google+, and Instagram, showing where on Earth they are and marking them with the hashtag #GlobalSelfie. Well, here we are a month later and the results have just been released… proof of what a beautiful world we all make up!

The image above was built using 36,422 fan-submitted self-portraits from 113 countries, and is based upon images of Earth acquired on April 22 by NASA/NOAA’s Visible Infrared Imaging Radiometer Suite instrument aboard the Suomi National Polar-orbiting Partnership (NPP) satellite. (See the original NPP images here.)

How cool is that? A picture of Earth, as seen from space, recomposed of pictures of people on Earth taken the very same day!

Did you send in a #GlobalSelfie? I’m in there somewhere too, but I haven’t located myself (yet). They’re organized by hue and tone, not location, so I could be representing a spot in the middle of the Peruvian jungle instead of along the Providence River.

View the full zoomable 3.2-gigapixel image on GigaPan here.

The GlobalSelfie campaign was more than just a PR gimmick. 2014 is a big year for NASA Earth observation, with five missions launched to monitor our planet’s wind, oceans, soil, and atmosphere. GlobalSelfie was used to kick off the Earth Right Now campaign, helping to raise awareness about these missions and the data they’ll gather to ultimately benefit people around the world.

Source: NASA/GSFC

The Newest ‘Earthrise’ Image, Courtesy of the Lunar Reconnaissance Orbiter

The Moon, tiny Earth and the vastness of space,as seen by the Lunar Reconnaissance Orbiter Wide Angle Camera (WAC). Credit: NASA/GSFC/Arizona State University.

That’s Earth. That’s us. Way off in the distance as a fairly small, blue and swirly white sphere. This is the newest so-called “Earthrise” image, and it was taken on February 1, 2014 by the Lunar Reconnaissance Orbiter.

“LRO experiences twelve earthrises every day, however LROC is almost always busy imaging the lunar surface so only rarely does an opportunity arise such that LROC can capture a view of the Earth,” wrote LROC Principal Investigator Mark Robinson on the instrument’s website. “On the first of February of this year LRO pitched forward while approaching the north pole allowing the LROC WAC to capture the Earth rising above Rozhdestvenskiy crater (180-km diameter).”

Robinson went on to explain that the Earth is a color composite from several frames and the colors are very close to what the average person would see if they were looking back at Earth themselves from lunar orbit. “Also, in this image the relative brightness between the Earth and the Moon is correct, note how much brighter the Earth is relative to the Moon,” Robinson said.

Gorgeous.

Below is a gif image that demonstrates how images are combined over several orbits to create a full image from the Wide Angle Camera.

A gif image showing the “venetian blind” banding demonstrates how a WAC image is built up frame-by-frame. The gaps between the frames are due to the real separation of the WAC filters on the CCD. Credit: NASA/GSFC/Arizona State University.

The frames were acquired at two second intervals, so the total time to collect the sequence was 5 minutes. The video is faster than reality by a factor of about 20.

Earth From Space: The Moon Over Mexico

The Moon over Mexico, taken March 12, 2014 from the International Space Station by astronaut Rick Mastracchio. Credit: NASA/Rick Mastracchio.

Happy Cinco de Mayo! This beautiful image of Earth from Space was taken earlier this year, but today is a perfect day to share it. ISS astronaut Rick Mastracchio snapped this photo of the waxing gibbous Moon on March 12, 2014.

The 5th of May commemorates a victory for Mexico in the Battle of Puebla in 1862 during the Franco-Mexican War. It wasn’t an especially crucial battle, but it became a symbol of Mexican pride and a celebration of Mexican culture in the United States. Cinco de Mayo isn’t widely celebrated in Mexico, but it is celebrated by many Americans regardless of their heritage (like St. Patrick’s Day and Oktoberfest).

This photo reminds us of the fragility and beauty of our world that we all inhabit together.

Via Fragile Oasis

HD Livestream of Earth Now Available 24/7 from the Space Station

Screenshot from the HDEV cameras on the International Space Station. Via @ISS101



Live streaming video by Ustream

Now, live from space, it’s Earth all the time! A new experiment called the High Definition Earth Viewing (HDEV) was launched on April 18, 2014 in the “trunk” on the SpaceX Dragon spacecraft and has been set up outside the International Space Station. The set of four commercial HD video cameras and is now operational, after being installed on the External Payload Facility of the ESA Columbus module yesterday. The cameras and electronics are enclosed in a pressurized box to provide protection to the equipment from the harsh environment of space.

Above is the UStream video, or you can bookmark the UStream site here, or view this page from Johnson Space Center which also provides a visual tracker of where the ISS is located over Earth.

Please note that the screen will appear black when the ISS is in orbital night — which happens every 90 minutes and lasts about 40 minutes. There also has been some downtime off and on that I’ve noted while watching this morning. This may be due to some initial setup/operation issues, or some occurrences of loss of signal. UPDATE: NASA’s now provided additional info on what’s happening if you’re not seeing beautiful views of Earth at anytime during the live feed: Black Scenes = Night side of the Earth; Gray Scenes = Switching to the next camera, or the communications downlink from the ISS in not available at the moment.

Also, the live video feed from HDEV will occasionally be unavailable due to loss of Ku-band transmission from the International Space Station. If that happens, just check the site again later.

But, having live HD streaming views of Earth is pretty awesome – but it’s also nifty to note that this is part of a student project.

High school students helped design of some of the HDEV components through the High Schools United with NASA to Create Hardware (HUNCH) program. Student teams will also help operate the experiment.

This experiment is completely separate from the UrtheCast commercial cameras on the ISS.

The HDEV does not record video on board the ISS, but all video is transmitted to the ground in real time. See the graphic below that explains how the cameras cycle automatically.

Part of the experiment is to test out the camera and equipment and assess the hardware’s ability to survive and function for long periods in space.

Enjoy!

HDEV11

How Life Could Have Produced Most Minerals On Earth

First ever image of Earth Taken by Mars Color Camera aboard India’s Mars Orbiter Mission (MOM) spacecraft while orbiting Earth and before the Trans Mars Insertion firing on Dec. 1, 2013. Image is focused on the Indian subcontinent. Credit: ISRO

While astronomers are trying to figure out which planets they find are habitable, there are a range of things to consider. How close are they to their parent star? What are their atmospheres made of? And once those answers are figured out, here’s something else to wonder about: how many minerals are on the planet’s surface?

In a talk today, the Carnegie Institution of Washington’s Robert Hazen outlined his findings showing that two-thirds  of minerals on Earth could have arisen from life itself. The concept is not new — he and his team first published on that in 2008 — but his findings came before the plethora of exoplanets discovered by the Kepler space telescope.

As more information is learned about these distant worlds, it will be interesting to see if it’s possible to apply his findings — if we could detect the minerals from afar in the first place.

“We live on a planet of remarkable beauty, and when you look at it from the proximity of our moon, you see what is obviously a very dynamic planet,” Hazen told delegates at “Habitable Worlds Across Time and Space”, a spring symposium from the Space Telescope Science Institute that is being webcast this week (April 28-May 1).

His point was that planets don’t necessarily start out that way, but he said in his talk that he’d invite comments and questions on his work for alternative processes. His team believes that minerals and life co-evolved: life became more complex and the number of minerals increased over time.

Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming.  Credit: ESO
Artist’s impression of a baby star still surrounded by a protoplanetary disc in which planets are forming. Credit: ESO

The first mineral in the cosmos was likely diamonds, which were formed in supernovas. These star explosions are where the heavier elements in our cosmos were created, making the universe more rich than its initial soup of hydrogen and helium.

There are in fact 10 elements that were key in the Earth’s formation, Hazen said, as well as that of other planets in our solar system (which also means that presumably these would apply to exoplanets). These were carbon, nitrogen, oxygen, magnesium, silicon, carbon, titanium, iron and nitrogen,which formed about a dozen minerals on the early Earth.

Here’s the thing, though. Today there are more than 4,900 minerals on Earth that are formed from 72 essential elements. Quite a change.

Hazen’s group proposes 10 stages of evolution:

  1. Primary chondrite minerals (4.56 billion years ago) – what was around as the solar nebula that formed our solar system cooled. 60 mineral species at this time.
  2. Planetesimals — or protoplanets — changed by impacts (4.56 BYA to 4.55 BYA). Here is where feldspars, micas, clays and quartz arose. 250 mineral  species.
  3. Planet formation (4.55 BYA to 3.5 BYA). On a “dry” planet like Mercury, evolution stopped at about 300 mineral species, while “wetter” planets like Mars would have seen about 420 mineral species that includes hydroxides and clays produced from processes such as volcanism and ices.
  4. Granite formation (more than 3.5 BYA). 1,000 mineral species including beryl and tantalite.
  5. Plate tectonics (more than 3 BYA). 1,500 mineral species. Increases produced from changes such as new types of volcanism and high-pressure metamorphic changes inside the Earth.
The official poster of the World Space Week Association 2013 campaign. Credit: World Space Week Association
The official poster of the World Space Week Association 2013 campaign. Credit: World Space Week Association

These stages above are about as far as you would get on a planet without life, Hazen said. As for the remaining stages on Earth, here they are:

  1. Anoxic biosphere (4 to 2.5 BYA), again with about 1,500 mineral species existing in the early atmosphere. Here was the rise of chemolithoautotrophs, or life that obtains energy from oxidizing inorganic compounds.
  2. Paleoproterozoic oxidation (2.5 to 1.5 BYA) — a huge rise in mineral species to 4,500 as oxygen becomes a dominant player in the atmosphere. “We’re trying to understand if this is really true for every other planet, or if there is alternative pathways,” Hazen said.

And the final three stages up to the present day was the emergence of large oceans, a global ice age and then (in the past 540 million years or so) biomineralization or the process of living organisms producing minerals. This latter stage included the development of tree roots, which led to species such as fungi, microbes and worms.

'The Moon rising behind a couple of palm trees with cows grazing in the foreground. As you can see in the image,  the bottom half of the moon has a different tint due to the earths atmosphere.' Credit:  Tom Connor, Parrish, FL
‘The Moon rising behind a couple of palm trees with cows grazing in the foreground. As you can see in the image, the bottom half of the moon has a different tint due to the earths atmosphere.’ Credit: Tom Connor, Parrish, FL

It should be noted here that oxygen does not necessarily indicate there is complex life. Fellow speaker David Catling from the University of Washington, however, noted that oxygen rose in the atmosphere about 2.4 billion years ago, coincident with the emergence of complex life.

Animals as we understand them could have been “impossible for most of Earth’s history because they couldn’t breathe,” he noted. But more study will be needed on this point. After all, we’ve only found life on one planet: Earth.

The STSCI conference continues through May 1; you can see the agenda here.