Gravitationalwaves - Blog Posts

Our Most “Liked” Instagram Posts of 2017

Our Instagram page has over 2,200 images and is lucky enough to be followed by more than 29 million fans.

What images and videos were your favorite from this past year? Great question, and one we asked ourselves too!

Here’s a look at our most liked Instagram posts* of 2017…Enjoy!

#10 Black Hole Collision

What happens when two supermassive black holes collide? Until last year, we weren’t quite sure. Gravitational waves!  With 834,169  likes, this image is our 10th most liked of 2017.

#9 Italy Through the Space Station Cupola Window

European astronaut Paolo Nespoli (@Astro_Paolo) shared this image on social media of "Southern #Italy and Sicily framed by one of our Cupola windows" aboard the International Space Station. This image ranks #9 for 2017 with 847,365 likes.

#8 Black Hole Friday

For our 5th annual #BlackHoleFriday we’ll share awesome images and facts about black holes! A black hole is a place in space where gravity pulls so much that even light cannot get out. With 916,247 likes, this picture ranks #8 for 2017.

#7 The Elements of Cassiopeia A

Did you know that stellar explosions and their remains--“supernova remnants”--are a source of chemical elements essential for life here on Earth? A new Chandra X-ray Observatory image captures the location of several vital elements like silicon (red), sulfur (yellow), calcium (green) and iron (purple), located on Cassiopeia A--a supernova remnant ~11,000 light years from Earth.  This image ranks #7 for 2017 with 943,806 likes.

#6 Jupiter Blues

Jupiter, you’re bluetiful 💙 ! Churning swirls of Jupiter’s clouds are seen in striking shades of blue in this new view taken by our Juno spacecraft. This image ranks as our sixth most liked Instagram post of 2017 with 990,944 likes.

#5 An Interstellar Visitor

An interstellar visitor…scientists have confirmed that an intriguing asteroid that zipped through our solar system in October is the first confirmed object from another star! Observations suggest that this unusual object had been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with our star system. With 1,015,721 likes, this image ranks #5 for 2017.

#4 Space Station Lunar Transit

Space station supermoon. This composite image made from six frames shows the International Space Station, with a crew of six onboard, as it transits the Moon at roughly five miles per second on Dec. 2. This image ranks #4 for 2017 with 1,037,520 likes.

#3 The Space Between Us

A post shared by NASA (@nasa) on Dec 20, 2017 at 2:56pm PST

The beautiful space between Earth and the International Space Station was immortalized by NASA astronaut Mark Vande Hei while orbiting 250 miles above the planet we call home. This majestic image ranks #3 for 2017 with 1,042,403 likes.

#2 The Moon Swallows the Sun

A post shared by NASA (@nasa) on Aug 21, 2017 at 2:03pm PDT

Today, the Sun disappeared, seemingly swallowed by our Moon–at least for a while. The August 21 solar eclipse cut through a swath of North America from coast to coast and those along the path of totality, that is where the Moon completely covered the Sun, were faced with a sight unseen in the U.S. in 99 years. Which might have something to do with this image ranking #2 for 2017 with 1,144,503 likes.

#1 Solar Eclipse Over Cascade Lake

A post shared by NASA (@nasa) on Aug 21, 2017 at 3:57pm PDT

Behold! This progression of the partial solar eclipse took place over Ross Lake, in Northern Cascades National Park, Washington on Monday, Aug. 21, 2017. 

This photo was our #1 image of 2017 with 1,471,114 likes!

See them all here!

Do you want to get amazing images of Earth from space, see distant galaxies and more on Instagram? Of course you do! Follow us: https://www.instagram.com/nasa/

*Posts and rankings are were taken as of Dec. 28, 2017.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

When Dead Stars Collide!

Gravity has been making waves - literally.  Earlier this month, the Nobel Prize in Physics was awarded for the first direct detection of gravitational waves two years ago. But astronomers just announced another huge advance in the field of gravitational waves - for the first time, we’ve observed light and gravitational waves from the same source.

There was a pair of orbiting neutron stars in a galaxy (called NGC 4993). Neutron stars are the crushed leftover cores of massive stars (stars more than 8 times the mass of our sun) that long ago exploded as supernovas. There are many such pairs of binaries in this galaxy, and in all the galaxies we can see, but something special was about to happen to this particular pair.

Each time these neutron stars orbited, they would lose a teeny bit of gravitational energy to gravitational waves. Gravitational waves are disturbances in space-time - the very fabric of the universe - that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction, like this pair of orbiting neutron stars. However, the gravitational waves are very faint unless the neutron stars are very close and orbiting around each other very fast.

As luck would have it, the teeny energy loss caused the two neutron stars to get a teeny bit closer to each other and orbit a teeny bit faster.  After hundreds of millions of years, all those teeny bits added up, and the neutron stars were *very* close. So close that … BOOM! … they collided. And we witnessed it on Earth on August 17, 2017.  

Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet

A couple of very cool things happened in that collision - and we expect they happen in all such neutron star collisions. Just before the neutron stars collided, the gravitational waves were strong enough and at just the right frequency that the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo could detect them. Just after the collision, those waves quickly faded out because there are no longer two things orbiting around each other!

LIGO is a ground-based detector waiting for gravitational waves to pass through its facilities on Earth. When it is active, it can detect them from almost anywhere in space.

The other thing that happened was what we call a gamma-ray burst. When they get very close, the neutron stars break apart and create a spectacular, but short, explosion. For a couple of seconds, our Fermi Gamma-ray Telescope saw gamma-rays from that explosion. Fermi’s Gamma-ray Burst Monitor is one of our eyes on the sky, looking out for such bursts of gamma-rays that scientists want to catch as soon as they’re happening.

And those gamma-rays came just 1.7 seconds after the gravitational wave signal. The galaxy this occurred in is 130 million light-years away, so the light and gravitational waves were traveling for 130 million years before we detected them.

After that initial burst of gamma-rays, the debris from the explosion continued to glow, fading as it expanded outward. Our Swift, Hubble, Chandra and Spitzer telescopes, along with a number of ground-based observers, were poised to look at this afterglow from the explosion in ultraviolet, optical, X-ray and infrared light. Such coordination between satellites is something that we’ve been doing with our international partners for decades, so we catch events like this one as quickly as possible and in as many wavelengths as possible.

Astronomers have thought that neutron star mergers were the cause of one type of gamma-ray burst - a short gamma-ray burst, like the one they observed on August 17. It wasn’t until we could combine the data from our satellites with the information from LIGO/Virgo that we could confirm this directly.

This event begins a new chapter in astronomy. For centuries, light was the only way we could learn about our universe. Now, we’ve opened up a whole new window into the study of neutron stars and black holes. This means we can see things we could not detect before.

The first LIGO detection was of a pair of merging black holes. Mergers like that may be happening as often as once a month across the universe, but they do not produce much light because there’s little to nothing left around the black hole to emit light. In that case, gravitational waves were the only way to detect the merger.

Image Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

The neutron star merger, though, has plenty of material to emit light. By combining different kinds of light with gravitational waves, we are learning how matter behaves in the most extreme environments. We are learning more about how the gravitational wave information fits with what we already know from light - and in the process we’re solving some long-standing mysteries!

Want to know more? Get more information HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

What are Gravitational Waves?

Today, the National Science Foundation (NSF) announced the detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO), a pair of ground-based observatories. But...what are gravitational waves? Let us explain:

Gravitational waves are disturbances in space-time, the very fabric of the universe, that travel at the speed of light. The waves are emitted by any mass that is changing speed or direction. The simplest example is a binary system, where a pair of stars or compact objects (like black holes) orbit their common center of mass.

We can think of gravitational effects as curvatures in space-time. Earth’s gravity is constant and produces a static curve in space-time. A gravitational wave is a curvature that moves through space-time much like a water wave moves across the surface of a lake. It is generated only when masses are speeding up, slowing down or changing direction.

Did you know Earth also gives off gravitational waves? Earth orbits the sun, which means its direction is always changing, so it does generate gravitational waves, although extremely weak and faint.

What do we learn from these waves?

Observing gravitational waves would be a huge step forward in our understanding of the evolution of the universe, and how large-scale structures, like galaxies and galaxy clusters, are formed.

Gravitational waves can travel across the universe without being impeded by intervening dust and gas. These waves could also provide information about massive objects, such as black holes, that do not themselves emit light and would be undetectable with traditional telescopes.

Just as we need both ground-based and space-based optical telescopes, we need both kinds of gravitational wave observatories to study different wavelengths. Each type complements the other.

Ground-based: For optical telescopes, Earth’s atmosphere prevents some wavelengths from reaching the ground and distorts the light that does.

Space-based: Telescopes in space have a clear, steady view. That said, telescopes on the ground can be much larger than anything ever launched into space, so they can capture more light from faint objects.

How does this relate to Einstein’s theory of relativity?

The direct detection of gravitational waves is the last major prediction of Einstein’s theory to be proven. Direct detection of these waves will allow scientists to test specific predictions of the theory under conditions that have not been observed to date, such as in very strong gravitational fields.

In everyday language, “theory” means something different than it does to scientists. For scientists, the word refers to a system of ideas that explains observations and experimental results through independent general principles. Isaac Newton's theory of gravity has limitations we can measure by, say, long-term observations of the motion of the planet Mercury. Einstein's relativity theory explains these and other measurements. We recognize that Newton's theory is incomplete when we make sufficiently sensitive measurements. This is likely also true for relativity, and gravitational waves may help us understand where it becomes incomplete.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com