Our latest space telescope, Transiting Exoplanet Survey Satellite (TESS), launched in April. This
week, planet hunters worldwide received all the data from the first two months
of its planet search. This view, from four cameras on TESS, shows just one
region of Earth’s southern sky.
The Transiting Exoplanet Survey Satellite (TESS) captured
this strip of stars and galaxies in the southern sky during one 30-minute
period in August. Created by combining the view from all four of its cameras, TESS
images will be used to discover new exoplanets. Notable features in this swath
include the Large and Small Magellanic Clouds and a globular cluster called NGC
104. The brightest stars, Beta Gruis and R Doradus, saturated an entire column
of camera detector pixels on the satellite’s second and fourth cameras.
The data in the images from TESS will soon lead to discoveries of
planets beyond our solar system – exoplanets. (We’re at 3,848 so far!)
But first, all that data (about 27 gigabytes a day) needs to be
processed. And where do space telescopes like TESS get their data cleaned up?
At the Star Wash, of course!
TESS sends about 10 billion pixels of data to Earth
at a time. A supercomputer at NASA Ames in Silicon Valley processes the raw
data, turning those pixels into measures of a star’s brightness.
And that brightness? THAT’S HOW WE FIND PLANETS! A dip in a star’s
brightness can reveal an orbiting exoplanet in transit.
TESS will spend a year studying our southern sky, then will turn
and survey our northern sky for another year. Eventually, the space telescope
will observe 85 percent of Earth’s sky, including 200,000 of the brightest and
closest stars to Earth.
Some people watch scary movies because they like being startled. A bad guy jumps out from around a corner! A monster emerges from the shadows! Scientists experience surprises all the time, but they’re usually more excited than scared. Sometimes theories foreshadow new findings — like when there’s a dramatic swell in the movie soundtrack — but often, discoveries are truly unexpected.
Scientists working with the Fermi Gamma-Ray Space Telescope have been jumping to study mysterious bumps in the gamma rays for a decade now. Gamma rays are the highest-energy form of light. Invisible to human eyes, they’re created by some of the most powerful and unusual events and objects in the universe. In celebration of Halloween, here are a few spooky gamma-ray findings from Fermi’s catalog.
If you were to walk through a cemetery at night, you’d expect to trip over headstones or grave markers. Maybe you’d worry about running into a ghost. If you could explore the stellar gravesite created when a star explodes as a supernova, you’d find a cloud of debris expanding into interstellar space. Some of the chemical elements in that debris, like gold and platinum, go on to create new stars and planets! Fermi found that supernova remnants IC 443 and W44 also accelerate mysterious cosmic rays, high-energy particles moving at nearly the speed of light. As the shockwave of the supernova expands, particles escape its magnetic field and interact with non-cosmic-ray particles to produce gamma rays.
But the sources of cosmic rays aren’t the only particle mysteries Fermi studies. Just this July, Fermi teamed up with the IceCube Neutrino Observatory in Antarctica to discover the first source of neutrinos outside our galactic neighborhood. Neutrinos are particles that weigh almost nothing and rarely interact with anything. Around a trillion of them pass through you every second, ghost-like, without you noticing and then continue on their way. (But don’t worry, like a friendly ghost, they don’t harm you!) Fermi traced the neutrino IceCube detected back to a supermassive black hole in a distant galaxy. By the time it reached Earth, it had traveled for 3.7 billion years at almost the speed of light!
Black Widow Pulsars
Black widows and redbacks are species of spiders with a reputation for devouring their partners. Astronomers have discovered two types of star systems that behave in a similar way. Sometimes when a star explodes as a supernova, it collapses back into a rapidly spinning, incredibly dense star called a pulsar. If there’s a lighter star nearby, it can get stuck in a close orbit with the pulsar, which blasts it with gamma rays, magnetic fields and intense winds of energetic particles. All these combine to blow clouds of material off the low-mass star. Eventually, the pulsar can eat away at its companion entirely.
What’s spookier than a good unsolved mystery? Dark matter is a little-understood substance that makes up most of the matter in the universe. The stuff that we can see — stars, people, haunted houses, candy — is made up of normal matter. But our surveys of the cosmos tell us there’s not enough normal matter to keep things working the way they do. There must be another type of matter out there holding everything together. One of Fermi’s jobs is to help scientists narrow down the search for dark matter. Last year, researchers noticed that most of the gamma rays coming from the Andromeda galaxy are confined to its center instead of being spread throughout. One possible explanation is that accumulated dark matter at the center of the galaxy is emitting gamma rays!
Just about every galaxy the size of our Milky Way (or bigger) has a supermassive black hole at its center. These objects are ginormous — hundreds of thousands to billions of times the mass of the Sun! Now, we know galaxies merge from time to time, so it follows that some of their black holes should combine too. But we haven’t seen a collision like that yet, and we don’t know exactly what it would look like.
A new simulation created on the Blue Waters supercomputer — which can do 13 quadrillion calculations per second, 3 million times faster than the average laptop — is helping scientists understand what kind of light would be produced by the gas around these systems as they spiral toward a merger.
The new simulation shows most of the light produced around these two black holes is UV or X-ray light. We can’t see those wavelengths with our own eyes, but many telescopes can. Models like this could tell the scientists what to look for.
You may have spotted the blank circular region between the two black holes. No, that’s not a third black hole. It’s a spot that wasn’t modeled in this version of the simulation. Future models will include the glowing gas passing between the black holes in that region, but the researchers need more processing power. The current version already required 46 days!
The supermassive black holes have some pretty nifty effects on the light created by the gas in the system. If you view the simulation from the side, you can see that their gravity bends light like a lens. When the black holes are lined up, you even get a double lens!
But what would the view be like from between two black holes? In the 360-degree video above, the system’s gas has been removed and the Gaia star catalog has been added to the background. If you watch the video in the YouTube app on your phone, you can moved the screen around to explore this extreme vista. Learn more about the new simulation here.
So you think you found an exoplanet – a planet around another star?
It’s not as simple as pointing a telescope to the sky and looking for a
planet that waves back. Scientists gather many observations and
carefully analyze their data before they can be even somewhat sure that
they’ve discovered new worlds.
Here are 10 things to know about finding
and confirming exoplanets.
This is an illustration of the different elements in our exoplanet
program, including ground-based observatories, like the W. M. Keck
Observatory, and space-based observatories like Hubble, Spitzer,
Kepler, TESS, James Webb Space Telescope, WFIRST and future missions.
1. Pick your tool to take a look.
The vast majority of planets around other stars have been found
through the transit method so far. This technique involves monitoring
the amount of light that a star gives off over time, and looking for
dips in brightness that may indicate an orbiting planet passing in front
of the star.
We have two specialized exoplanet-hunting telescopes scanning the
sky for new planets right now – Kepler and the Transiting Exoplanet
Survey Satellite (TESS) – and they both work this way. Other methods of
finding exoplanets include radial velocity (looking for a “wobble” in a
star’s position caused by a planet’s gravity), direct imaging (blocking
the light of the star to see the planet) and microlensing (watching for
events where a star passes in front of another star, and the gravity of
the first star acts as a lens).
To find a planet, scientists need to get data from telescopes,
whether those telescopes are in space or on the ground. But telescopes
don’t capture photos of planets with nametags. Instead, telescopes
designed for the transit method show us how brightly thousands of stars
are shining over time. TESS, which launched in April and just began
collecting science data, beams its stellar observations back to Earth
through our Deep Space Network, and then scientists get to work.
3. Scan the data for planets.
Researchers combing through TESS data are looking for those transit
events that could indicate planets around other stars. If the star’s
light lessens by the same amount on a regular basis – for example,
every 10 days – this may indicate a planet with an orbital period (or
“year”) of 10 days. The standard requirement for planet candidates from
TESS is at least two transits – that is, two equal dips in brightness
from the same star.
4. Make sure the planet signature couldn’t be something else.
Not all dips in a star’s brightness are caused by transiting planets.
There may be another object – such as a companion star, a group of
asteroids, a cloud of dust or a failed star called a brown dwarf, that
makes a regular trip around the target star. There could also be
something funky going on with the telescope’s behavior, how it delivered
the data, or other “artifacts” in data that just aren’t planets.
Scientists must rule out all non-planet options to the best of their
ability before moving forward.
5. Follow up with a second detection method.
Finding the same planet candidate using two different techniques is a
strong sign that the planet exists, and is the standard for
“confirming” a planet. That’s why a vast network of ground-based
telescopes will be looking for the same planet candidates that TESS
discovers. It is also possible that TESS will spot a planet candidate
already detected by another telescope in the past. With these combined
observations, the planet could then be confirmed. The first planet TESS
discovered, Pi Mensae c, orbits a star previously observed with the
radial-velocity method on the ground. Scientists compared the TESS data
and the radial-velocity data from that star to confirm the presence of
Scientists using the radial-velocity detection method see a star’s
wobble caused by a planet’s gravity, and can rule out other kinds of
objects such as companion stars. Radial-velocity detection also allows
scientists to calculate the mass of the planet.
6. …or at least another telescope.
Other space telescopes may also be used to help confirm exoplanets,
characterize them and even discover additional planets around the same
stars. If the planet is detected by the same method, but by two
different telescopes, and has received enough scrutiny that the
scientists are more than 99 percent sure it’s a planet, it is said to be
“validated” instead of “confirmed.”
7. Write a paper.
After thoroughly analyzing the data, and running tests to make sure
that their result still looks like the signature of a planet, scientists
write a formal paper describing their findings. Using the transit
method, they can also report the size of the planet. The planet’s radius
is related to how much light it blocks from the star, as well as the
size of the star itself. The scientists then submit the study to a
8. Wait for peer review.
Scientific journals have a rigorous peer review process. This means
scientific experts not involved in the study review it and make sure the
findings look sound. The peer-reviewers may have questions or
suggestions for the scientists. When everyone agrees on a version of the
study, it gets published.
9. Publish the study.
When the study is published, scientists can officially say they have
found a new planet. This may still not be the end of the story, however.
For example, the TRAPPIST telescope in Chile first thought they had
discovered three Earth-size planets in the TRAPPIST-1 system.
When our Spitzer Space Telescope and other ground-based telescopes
followed up, they found that one of the original reported planets (the
original TRAPPIST-1d) did not exist, but they discovered five others
–bringing the total up to seven wondrous rocky worlds.
10. Catalog and celebrate – and look closer if you can!
Confirmed planets get added to our official catalog. So far,
Kepler has sent back the biggest bounty of confirmed exoplanets of any
telescope – more than 2,600 to date. TESS, which just began its planet
search, is expected to discover many thousands more. Ground-based
follow-up will help determine if these planets are gaseous or rocky, and
possibly more about their atmospheres. The forthcoming James Webb Space
Telescope will be able to take a deeper look at the atmospheres of the
most interesting TESS discoveries.
Scientists sometimes even uncover planets with the help of people like you: exoplanet K2-138 was discovered through citizen scientists
in Kepler’s K2 mission data. Based on surveys so far, scientists
calculate that almost every star in the Milky Way should have at least
one planet. That makes billions more, waiting to be found! Stay up to
date with our latest discoveries using this exoplanet counter.
Our Spitzer Space Telescope is celebrating 15 years since its launch on August 25, 2003. This remarkable spacecraft has made discoveries its designers never even imagined, including some of the seven Earth-size planets of TRAPPIST-1. Here are some key facts about Spitzer:
1. Spitzer is one of our Great Observatories.
Our Great Observatory Program aimed to explore the universe with four large space telescopes, each specialized in viewing the universe in different wavelengths of light. The other Great Observatories are our Hubble Space Telescope, Chandra X-Ray Observatory, and Compton Gamma-Ray Observatory. By combining data from different kinds of telescopes, scientists can paint a fuller picture of our universe.
2. Spitzer operates in infrared light.
Infrared wavelengths of light, which primarily come from heat radiation, are too long to be seen with human eyes, but are important for exploring space — especially when it comes to getting information about something extremely far away. From turbulent clouds where stars are born to small asteroids close to Earth’s orbit, a wide range of phenomena can be studied in infrared light. Objects too faint or distant for optical telescopes to detect, hidden by dense clouds of space dust, can often be seen with Spitzer. In this way, Spitzer acts as an extension of human vision to explore the universe, near and far.
What’s more, Spitzer doesn’t have to contend with Earth’s atmosphere, daily temperature variations or day-night cycles, unlike ground-based telescopes. With a mirror less than 1 meter in diameter, Spitzer in space is more sensitive than even a 10-meter-diameter telescope on Earth.
3. Spitzer was the first spacecraft to fly in an Earth-trailing orbit.
Rather than circling Earth, as Hubble does, Spitzer orbits the Sun on almost the same path as Earth. But Spitzer moves slower than Earth, so the spacecraft drifts farther away from our planet each year.
This “Earth-trailing orbit” has many advantages. Being farther from Earth than a satellite, it receives less heat from our planet and enjoys a naturally cooler environment. Spitzer also benefits from a wider view of the sky by orbiting the Sun. While its field of view changes throughout the year, at any given time it can see about one-third of the sky. Our Kepler space telescope, famous for finding thousands of exoplanets – planets outside our solar system – also settled in an Earth-trailing orbit six years after Spitzer.
4. Spitzer began in a “cold mission.”
Spitzer has far outlived its initial requirement of 2.5 years. The Spitzer team calls the first 5.5 years “the cold mission” because the spacecraft’s instruments were deliberately cooled down during that time. Liquid helium coolant kept Spitzer’s instruments just a few degrees above absolute zero (which is minus 459 degrees Fahrenheit, or minus 273 degrees Celsius) in this first part of the mission.
5. The “warm mission” was still pretty cold.
Spitzer entered what was called the “warm mission” when the 360 liters of liquid helium coolant that was chilling its instruments ran out in May 2009.
At the “warm” temperature of minus 405 Fahrenheit, two of Spitzer’s instruments – the Infrared Spectrograph (IRS) and Multiband Imaging Photometer (MIPS) – stopped working. But two of the four detector arrays in the Infrared Array Camera (IRAC) persisted. These “channels” of the camera have driven Spitzer’s explorations since then.
6. Spitzer wasn’t designed to study exoplanets, but made huge strides in this area.
Exoplanet science was in its infancy in 2003 when Spitzer launched, so the mission’s first scientists and engineers had no idea it could observe planets beyond our solar system. But the telescope’s accurate star-targeting system and the ability to control unwanted changes in temperature have made it a useful tool for studying exoplanets. During the Spitzer mission, engineers have learned how to control the spacecraft’s pointing more precisely to find and characterize exoplanets, too.
Using what’s called the “transit method,” Spitzer can stare at a star and detect periodic dips in brightness that happen when a planet crosses a star’s face. In one of its most remarkable achievements, Spitzer discovered three of the TRAPPIST-1 planets and confirmed that the system has seven Earth-sized planets orbiting an ultra-cool dwarf star. Spitzer data also helped scientists determine that all seven planets are rocky, and made these the best-understood exoplanets to date.
Spitzer can also use a technique called microlensing to find planets closer to the center of our galaxy. When a star passes in front of another star, the gravity of the first star can act as a lens, making the light from the more distant star appear brighter. Scientists are using microlensing to look for a blip in that brightening, which could mean that the foreground star has a planet orbiting it. Microlensing could not have been done early in the mission when Spitzer was closer to Earth, but now that the spacecraft is farther away, it has a better chance of measuring these events.
7. Spitzer is a window into the distant past.
The spacecraft has observed and helped discover some of the most distant objects in the universe, helping scientists understand where we came from. Originally, Spitzer’s camera designers had hoped the spacecraft would detect galaxies about 12 billion light-years away. In fact, Spitzer has surpassed that, and can see even farther back in time – almost to the beginning of the universe. In collaboration with Hubble, Spitzer helped characterize the galaxy GN-z11 about 13.4 billion light-years away, whose light has been traveling since 400 million years after the big bang. It is the farthest galaxy known.
8. Spitzer discovered Saturn’s largest ring.
Everyone knows Saturn has distinctive rings, but did you know its largest ring was only discovered in 2009, thanks to Spitzer? Because this outer ring doesn’t reflect much visible light, Earth-based telescopes would have a hard time seeing it. But Spitzer saw the infrared glow from the cool dust in the ring. It begins 3.7 million miles (6 million kilometers) from Saturn and extends about 7.4 million miles (12 million kilometers) beyond that.
9. The “Beyond Phase” pushes Spitzer to new limits.
In 2016, Spitzer entered its “Beyond phase,” with a name reflecting how the spacecraft operates beyond its original scope.
As Spitzer floats away from Earth, its increasing distance presents communication challenges. Engineers must point Spitzer’s antenna at higher angles toward the Sun in order to talk to our planet, which exposes the spacecraft to more heat. At the same time, the spacecraft’s solar panels receive less sunlight because they point away from the Sun, putting more stress on the battery.
The team decided to override some autonomous safety systems so Spitzer could continue to operate in this riskier mode. But so far, the Beyond phase is going smoothly.
10. Spitzer paves the way for future infrared telescopes.
Spitzer has identified areas of further study for our upcoming James Webb Space Telescope, planned to launch in 2021. Webb will also explore the universe in infrared light, picking up where Spitzer eventually will leave off. With its enhanced ability to probe planetary atmospheres, Webb may reveal striking new details about exoplanets that Spitzer found. Distant galaxies unveiled by Spitzer together with other telescopes will also be observed in further detail by Webb. The space telescope we are planning after that, WFIRST, will also investigate long-standing mysteries by looking at infrared light. Scientists planning studies with future infrared telescopes will naturally build upon the pioneering legacy of Spitzer.
Read the web version of this week’s “Solar System: 10 Things to Know” article HERE.
Astronomers James Christy and Robert Harrington weren’t even looking for satellites of Pluto when they discovered Charon in June 1978 at the U.S. Naval Observatory Flagstaff Station in Arizona – only about six miles from where Pluto was discovered at Lowell Observatory. Instead, they were trying to refine Pluto’s orbit around the Sun when sharp-eyed Christy noticed images of Pluto were strangely elongated; a blob seemed to move around Pluto.
The direction of elongation cycled back and forth over 6.39 days―the same as Pluto’s rotation period. Searching through their archives of Pluto images taken years before, Christy then found more cases where Pluto appeared elongated. Additional images confirmed he had discovered the first known moon of Pluto.
2. Forever and Always
Christy proposed the name Charon after the mythological ferryman who carried souls across the river Acheron, one of the five mythical rivers that surrounded Pluto’s underworld. But Christy also chose it for a more personal reason: The first four letters matched the name of his wife, Charlene. (Cue the collective sigh.)
3. Big Little Moon
Charon—the largest of Pluto’s five moons and approximately the size of Texas—is almost half the size of Pluto itself. The little moon is so big that Pluto and Charon are sometimes referred to as a double dwarf planet system. The distance between them is 12,200 miles (19,640 kilometers).
4. A Colorful and Violent History
Many scientists on the New Horizons mission expected Charon to be a monotonous, crater-battered world; instead, they found a landscape covered with mountains, canyons, landslides, surface-color variations and more. High-resolution images of the Pluto-facing hemisphere of Charon, taken by New Horizons as the spacecraft sped through the Pluto system on July 14 and transmitted to Earth on Sept. 21, reveal details of a belt of fractures and canyons just north of the moon’s equator.
5. Grander Canyon
This great canyon system stretches more than 1,000 miles (1,600 kilometers) across the entire face of Charon and likely around onto Charon’s far side. Four times as long as the Grand Canyon, and twice as deep in places, these faults and canyons indicate a titanic geological upheaval in Charon’s past.
6. Officially Official
In April 2018, the International Astronomical Union—the internationally recognized authority for naming celestial bodies and their surface features—approved a dozen names for Charon’s features proposed by our New Horizons mission team. Many of the names focus on the literature and mythology of exploration.
7. Flying Over Charon
This flyover video of Charon was created thanks to images from our New Horizons spacecraft. The “flight” starts with the informally named Mordor (dark) region near Charon’s north pole. Then the camera moves south to a vast chasm, descending to just 40 miles (60 kilometers) above the surface to fly through the canyon system.
8. Strikingly Different Worlds
This composite of enhanced color images of Pluto (lower right) and Charon (upper left), was taken by New Horizons as it passed through the Pluto system on July 14, 2015. This image highlights the striking differences between Pluto and Charon. The color and brightness of both Pluto and Charon have been processed identically to allow direct comparison of their surface properties, and to highlight the similarity between Charon’s polar red terrain and Pluto’s equatorial red terrain.
9. Quality Facetime
Charon neither rises nor sets, but hovers over the same spot on Pluto’s surface, and the same side of Charon always faces Pluto―a phenomenon called mutual tidal locking.
10. Shine On, Charon
Bathed in “Plutoshine,” this image from New Horizons shows the night side of Charon against a star field lit by faint, reflected light from Pluto itself on July 15, 2015.
Read the full version of this week’s ‘10 Things to Know’ article on the web HERE.
In 2016, Fermi showed the Moon is brighter in gamma rays than the Sun. Because the Moon doesn’t have a magnetic field, the surface is constantly pelted from all directions by cosmic rays. These produce gamma rays when they run into other particles, causing a full-Moon gamma-ray glow.
Many galaxies, including our own, have black holes at their centers. In active galaxies, dust and gas fall into and “feed” the black hole, releasing light and heat. In 2015 for the first time, scientists using Fermi data found hints that a galaxy called PG 1553+113 has a years-long gamma-ray emission cycle. They’re not sure what causes this cycle, but one exciting possibility is that the galaxy has a second supermassive black hole that causes periodic changes in what the first is eating.
Gamma-ray bursts are the most luminous explosions in the universe. In 2013, Fermi spotted the brightest burst it’s seen so far in the constellation Leo. In the first three seconds alone, the burst, called GRB 130427A, was brighter than any other burst seen before it. This record has yet to be shattered.
We can directly observe only 20 percent of the matter in the universe. The rest is invisible to telescopes and is called dark matter — and we’re not quite sure what it is. In 2012, Fermi helped place new limits on the properties of dark matter, essentially narrowing the field of possible particles that can describe what dark matter is.
SOFIA is a Boeing 747SP aircraft with a 100-inch telescope used to study the solar system and beyond by observing infrared light that can’t reach Earth’s surface.
What is infrared light? It’s light we cannot see with our eyes that is just beyond the red portion of visible light we see in a rainbow. It can be used to change your TV channels, which is how remote controls work, and it can tell us how hot things are.
Everything emits infrared radiation, even really cold objects like ice and newly forming stars! We use infrared light to study the life cycle of stars, the area around black holes, and to analyze the chemical fingerprints of complex molecules in space and in the atmospheres of other planets – including Pluto and Mars.
Above, is the highest-resolution image of the ring of dust and clouds around the back hole at the center of our Milky Way Galaxy. The bright Y-shaped feature is believed to be material falling from the ring into the black hole – which is located where the arms of the Y intersect.
The magnetic field in the galaxy M82 (pictured above) aligns with the dramatic flow of material driven by a burst of star formation. This is helping us learn how star formation shapes magnetic fields of an entire galaxy.
A nearby planetary system around the star Epsilon Eridani, the location of the fictional Babylon 5 space station, is similar to our own: it’s the closest known planetary system around a star like our sun and it also has an asteroid belt adjacent to the orbit of its largest, Jupiter-sized planet.
Observations of a supernova that exploded 10,000 years ago, that revealed it contains enough dust to make 7,000 Earth-sized planets!
A gluttonous star that has eaten the equivalent of 18 Jupiters in the last 80 years, which may change the theory of how stars and planets form.
Molecules like those in your burnt breakfast toast may offer clues to the building blocks of life. Scientists hypothesize that the growth of complex organic molecules like these is one of the steps leading to the emergence of life.
This map of carbon molecules in Orion’s Horsehead nebula (overlaid on an image of the nebula from the Palomar Sky Survey) is helping us understand how the earliest generations of stars formed. Our instruments on SOFIA use 14 detectors simultaneously, letting us make this map faster than ever before!
Pinpointing the location of water vapor in a newly forming star with groundbreaking precision. This is expanding our understanding of the distribution of water in the universe and its eventual incorporation into planets. The water vapor data from SOFIA is shown above laid over an image from the Gemini Observatory.
We captured the chemical fingerprints that revealed celestial clouds collapsing to form young stars like our sun. It’s very rare to directly observe this collapse in motion because it happens so quickly. One of the places where the collapse was observed is shown in this image from The Two Micron All Sky Survey.
A flash of lightning. A roll of thunder. These are normal stormy sights and sounds. But sometimes, up above the clouds, stranger things happen. Our Fermi Gamma-ray Space Telescope has spotted bursts of gamma rays – some of the highest-energy forms of light in the universe – coming from thunderstorms. Gamma rays are usually found coming from objects with crazy extreme physics like neutron stars and black holes.
So why is Fermi seeing them come from thunderstorms?
Thunderstorms form when warm, damp air near the ground starts to rise and encounters colder air. As the warm air rises, moisture condenses into water droplets. The upward-moving water droplets bump into downward-moving ice crystals, stripping off electrons and creating a static charge in the cloud.
The top of the storm becomes positively charged, and the bottom becomes negatively charged, like two ends of a battery. Eventually the opposite charges build enough to overcome the insulating properties of the surrounding air – and zap! You get lightning.
When those electrons run into air molecules, they emit a terrestrial gamma-ray flash, which means that thunderstorms are creating some of the highest energy forms of light in the universe. But that’s not all – thunderstorms can also produce antimatter! Yep, you read that correctly! Sometimes, a gamma ray will run into an atom and produce an electron and a positron, which is an electron’s antimatter opposite!
The Fermi Gamma-ray Space Telescope can spot terrestrial gamma-ray flashes within 500 miles of the location directly below the spacecraft. It does this using an instrument called the Gamma-ray Burst Monitor which is primarily used to watch for spectacular flashes of gamma rays coming from the universe.
There are an estimated 1,800 thunderstorms occurring on Earth at any given moment. Over the 10 years that Fermi has been in space, it has spotted about 5,000 terrestrial gamma-ray flashes. But scientists estimate that there are 1,000 of these flashes every day – we’re just seeing the ones that are within 500 miles of Fermi’s regular orbits, which don’t cover the U.S. or Europe.
The map above shows all the flashes Fermi has seen since 2008. (Notice there’s a blob missing over the lower part of South America. That’s the South Atlantic Anomaly, a portion of the sky where radiation affects spacecraft and causes data glitches.)
Fermi has also spotted terrestrial gamma-ray flashes coming from individual tropical weather systems. The most productive system we’ve seen was Tropical Storm Julio in 2014, which later became a hurricane. It produced four flashes in just 100 minutes!
Our Transiting Exoplanet Survey Satellite (TESS), which will scan the skies to look for planets beyond our solar system—known as exoplanets—is now in Florida to begin preparations for launch in April. Below, 10 Things to know about the many, many unknown planets out there awaiting our discovery.
We call planets in our solar system, well, planets, but the many planets we’re starting to discover outside of our solar system are called exoplanets. Basically, they’re planets that orbit another star.
2—All eyes on TRAPPIST-1.
Remember the major 2016 announcement that we had discovered seven planets 40 light-years away, orbiting a star called TRAPPIST-1? Those are all exoplanets. (Here’s a refresher.)
3—Add 95 new ones to that.
Just last month, our Kepler telescope discovered 95 new exoplanets beyond our solar system (on top of the thousands of exoplanets Kepler has discovered so far). The total known planet count beyond our solar system is now more than 3,700. The planets range in size from mostly rocky super-Earths and fluffy mini-Neptunes, to Jupiter-like giants. They include a new planet orbiting a very bright star—the brightest star ever discovered by Kepler to have a transiting planet.
4—Here comes TESS.
How many more exoplanets are out there waiting to be discovered? TESS will monitor more than 200,000 of the nearest and brightest stars in search of transit events—periodic dips in a star’s brightness caused by planets passing in front—and is expected to find thousands of exoplanets.
5—With a sidekick, too.
Ourupcoming James Webb Space Telescope, will provide important follow-up observations of some of the most promising TESS-discovered exoplanets. It will also allow scientists to study their atmospheres and, in some special cases, search for signs that these planets could support life.
6—Prepped for launch.
TESS is scheduled to launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station nearby our Kennedy Space Center in Florida, no earlier than April 16, pending range approval.
7—A groundbreaking find.
In 1995, 51 Pegasi b (also called “Dimidium”) was the first exoplanet discovered orbiting a star like our Sun. This find confirmed that planets like the ones in our solar system could exist elsewhere in the universe.
A recent statistical estimate places, on average, at least one planet around every star in the galaxy. That means there could be a trillion planets in our galaxy alone, many of them in the range of Earth’s size.
9—Signs of life.
Of course, our ultimate science goal is to find unmistakable signs of current life. How soon can that happen? It depends on two unknowns: the prevalence of life in the galaxy and a bit of luck. Read more about the search for life.