When we think about what makes a planet habitable, we’re often talking about water. With abundant water in liquid, gas (vapor) and solid (ice) form, Earth is a highly unusual planet. Almost 70% of our home planet’s surface is covered in water!
But about 97% of Earth’s water is salty – only a tiny amount is freshwater: the stuff humans, pets and plants need to survive.
Water on our planet is constantly moving, and not just geographically. Water shifts phases from ice to water to vapor and back, moving through the planet’s soils and skies as it goes.
That’s where our satellites come in.
Look at the Midwestern U.S. this spring, for example. Torrential rain oversaturated the soil and overflowed rivers, which caused severe flooding, seen by Landsat.
Our satellites also tracked a years-long drought in California. Between 2013 and 2014, much of the state turned brown, without visible green.
It’s not just rain. Where and when snow falls – and melts – is changing, too. The snow that falls and accumulates on the ground is called snowpack, which eventually melts and feeds rivers used for drinking water and crop irrigation. When the snow doesn’t fall, or melts too early, communities go without water and crops don’t get watered at the right time.
Even when water is available, it can become contaminated by blooms of phytoplankton, like cyanobacteria . Also known as blue-green algae, these organisms can make humans sick if they drink the water. Satellites can help track algae from space, looking for the brightly colored blooms against blue water.
Zooming even farther back, Earth’s blue water is visible from thousands of miles away. The water around us makes our planet habitable and makes our planet shine blue among the darkness of space.
Knowing where the water is, and where it’s going, helps people make better decisions about how to manage it. Earth’s climate is changing rapidly, and freshwater is moving as a result. Some places are getting drier and some are getting much, much wetter. By predicting droughts and floods and tracking blooms of algae, our view of freshwater around the globe helps people manage their water.
Ten years ago, on March 6, 2009, a rocket lifted off a launch pad at Cape Canaveral Air Force Station in Florida. It carried a passenger that would revolutionize our understanding of our place in the cosmos–NASA’s first planet hunter, the Kepler space telescope. The spacecraft spent more than nine years in orbit around the Sun, collecting an unprecedented dataset for science that revealed our galaxy is teeming with planets. It found planets that are in some ways similar to Earth, raising the prospects for life elsewhere in the cosmos, and stunned the world with many other first-of-a-kind discoveries. Here are five facts about the Kepler space telescope that will blow you away:
Kepler observed more than a half million stars looking for planets beyond our solar system.
It discovered more than 2,600 new worlds…
…many of which could be promising places for life.
Kepler’s survey revealed there are more planets than stars in our galaxy.
The spacecraft is now drifting around the Sun more than 94 million miles away from Earth in a safe orbit.
Our solar system was built on impacts — some big, some small — some fast, some slow. This week, in honor of a possible newly-discovered large crater here on Earth, here’s a quick run through of some of the more intriguing impacts across our solar system.
1. Mercury: A Basin Bigger Than Texas
Mercury does not have a thick atmosphere to protect it from space debris. The small planet is riddled with craters, but none as spectacular as the Caloris Basin. “Basin” is what geologists call craters larger than about 186 miles (300 kilometers) in diameter. Caloris is about 950 miles (1,525 kilometers) across and is ringed by mile-high mountains.
For scale, the state of Texas is 773 miles (1,244 kilometers) wide from east to west.
2. Venus: Tough on Space Rocks
Venus’ ultra-thick atmosphere finishes off most meteors before they reach the surface. The planet’s volcanic history has erased many of its craters, but like almost any place with solid ground in our solar system, there are still impact scars to be found. Most of what we know of Venus’ craters comes from radar images provided by orbiting spacecraft, such as NASA’s Magellan.
Mead Crater is the largest known impact site on Venus. It is about 170 miles (275 kilometers) in diameter. The relatively-flat, brighter inner floor of the crater indicates it was filled with impact melt and/or lava.
3. Earth: Still Craters After All These Years
Evidence of really big impacts — such as Arizona’s Meteor Crater — are harder to find on Earth. The impact history of our home world has largely been erased by weather and water or buried under lava, rock or ice. Nonetheless, we still find new giant craters occasionally.
This follows the finding, announced in November 2018, of a 19-mile (31-kilometer) wide crater beneath Hiawatha Glacier – the first meteorite impact crater ever discovered under Earth’s ice sheets.
If the second crater, which has a width of over 22 miles (35 kilometers), is ultimately confirmed as the result of a meteorite impact, it will be the 22nd largest impact crater found on Earth.
4. Moon: Our Cratered Companion
Want to imagine what Earth might look like without its protective atmosphere, weather, water and other crater-erasing features? Look up at the Moon. The Moon’s pockmarked face offers what may be humanity’s most familiar view of impact craters.
One of the easiest to spot is Tycho, the tight circle and bright, radiating splat are easy slightly off center on the lower-left side of the full moon. Closer views of the 53-mile (85 kilometer)-wide crater from orbiting spacecraft reveal a beautiful central peak, topped with an intriguing boulder that would fill about half of a typical city block.
5. Mars: Still Taking Hits
Mars has just enough atmosphere to ensure nail-biting spacecraft landings, but not enough to prevent regular hits from falling space rocks. This dark splat on the Martian south pole is less than a year old, having formed between July and September 2018. The two-toned blast pattern tells a geologic story. The larger, lighter-colored blast pattern could be the result of scouring by winds from the impact shockwave on ice. The darker-colored inner blast pattern is because the impactor penetrated the thin ice layer, blasting the dark sand underneath in all directions.
6. Ceres: What Lies Beneath
The bright spots in Ceres’ Occator crater intrigued the world from the moment the approaching Dawn spacecraft first photographed it in 2015. Closer inspection from orbit revealed the spots to be the most visible example of hundreds of bright, salty deposits that decorate the dwarf planet like a smattering of diamonds. The science behind these bright spots is even more compelling: they are mainly sodium carbonate and ammonium chloride that somehow made their way to the surface in a slushy brine from within or below the crust. Thanks to Dawn, scientists have a better sense of how these reflective areas formed and changed over time — processes indicative of an active, evolving world.
7. Comet Tempel 1: We Did It!
Scientists have long known we can learn a lot from impact craters — so, in 2005, they made one themselves and watched it happen.
On July 4, 2005, NASA’s Deep Impact spacecraft trained its instruments on an 816-pound (370-kilogram) copper impactor as it smashed into comet Tempel 1.
One of the more surprising findings: The comet has a loose, “fluffy” structure, held together by gravity and contains a surprising amount of organic compounds that are part of the basic building blocks of life.
8. Mimas: May the 4th Be With You
Few Star Wars fans — us included — can resist Obi Wan Kenobi’s memorable line “That’s no moon…” when images of Saturn’s moon Mimas pop up on a screen. Despite its Death Star-like appearance, Mimas is most definitely a moon. Our Cassini spacecraft checked, a lot — and the superlaser-looking depression is simply an 81-mile (130-kilometer) wide crater named for the moon’s discoverer, William Herschel.
9. Europa: Say What?
The Welsh name of this crater on Jupiter’s ocean moon Europa looks like a tongue-twister, but it is easiest pronounced as “pool.” Pwyll is thought to be one of the youngest features we know of on Europa. The bright splat from the impact extends more than 600 miles (about 1,000 kilometers) around the crater, a fresh blanket over rugged, older terrain. “Fresh,” or young, is a relative term in geology; the crater and its rays are likely millions of years old.
10. Show Us Your Greatest Hits
Got a passion for Stickney, the dominant bowl-shaped crater on one end of Mars’ moon Phobos? Or a fondness for the sponge-like abundance of impacts on Saturn’s battered moon Hyperion (pictured)? There are countless craters to choose from. Share your favorites with us on Twitter, Instagram and Facebook.
2018 was the fourth hottest year since modern recordkeeping
began. NASA and the National Oceanic and Atmospheric Administration work together to track temperatures around the world and
study how they change from year to year. For decades, the overall global temperature
has been increasing.
Over the long term, world temperatures are warming, but each
individual year is affected by things like El Niño ocean patterns and specific
Globally, Earth’s temperature was more than 1.5 degrees
Fahrenheit warmer than the average from 1951 to 1980.
Since 1880, we can put together a consistent
record of temperatures around the planet and see that it was much colder in the
Before 1880, uncertainties in tracking global temperatures were too large.
Temperatures have increased even faster since the 1970s, the result of
increasing greenhouse gases in the atmosphere.
The last five years have been the hottest in the modern
Scientists from NASA use data from 6,300 weather stations
and Antarctic research stations, together with ship- and buoy-based
observations of sea surface temperatures to track global temperatures.
We’ve discovered thousands of exoplanets – planets beyond our solar system – so far. These worlds are mysterious, but observations from telescopes on the ground and in space help us understand what they might look like.
Take the planet 55 Cancri e, for instance. It’s relatively close, galactically speaking, at 41 light-years away. It’s a rocky planet, nearly two times bigger than Earth, that whips around its star every 18 hours (as opposed to the 365 days it takes our planet to orbit the Sun. Slacker).
The planet’s star, 55 Cancri, is slightly smaller than our Sun, but it’s 65 times closer than the Sun is to Earth. Imagine a massive sun on the horizon! Because 55 Cancri e is so close to its star, it’s tidally locked just like our Moon is to the Earth. One side is always bathed in daylight, the other is in perpetual darkness. It’s also hot. Really hot. So hot that silicate rocks would melt into a molten ocean of melted rock. IT’S COVERED IN AN OCEAN OF LAVA. So, it’s that hot (between 3,140 degrees and 2,420 degrees F).
Scientists think 55 Cancri e also may harbor a thick atmosphere that circulates heat from the dayside to the nightside. Silicate vapor in the atmosphere could condense into sparkling clouds on the cooler, darker nightside that would reflect the lava below. It’s also possible that it would rain sand on the nightside, but … sparkling skies!
Check out our Exoplanet Travel Bureau’s latest 360-degree visualization of 55 Cancri e and download the travel poster at https://go.nasa.gov/2HOyfF3.
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.
I never get tired of this photo, and will post it again and again. In the words of Carl Sagan…a pale blue dot.
Take a moment to contemplate our home in the grand scheme of the universe. In the middle of petty squabbles and power grabs, in the end, we are adrift on our cosmic journey. We need to take better care of our “spaceship”.
And for those who do not care or would not hesitate to screw our home over to make some money, I’d love to banish you to Venus.
has taught us there are so many planets out there, they outnumber even
the stars. Here is a sample of these wondrous, weird and unexpected worlds (and
other spectacular objects in space) that Kepler has spotted with its “eye” opened to the heavens.
Kepler has found that double sunsets
really do exist.
Yes, Star Wars fans, the double sunset on Tatooine could really exist.
Kepler discovered the first known planet around a double-star system, though
Kepler-16b is probably a gas giant without a solid surface.
Kepler has gotten us closer to finding
planets like Earth.
Nope. Kepler hasn’t found Earth 2.0, and that wasn’t the job it set out
to do. But in its survey of hundreds of thousands of stars, Kepler found planets
near in size to Earth orbiting at a distance where liquid water could pool on
the surface. One of them, Kepler-62f, is about 40 percent bigger than Earth and
is likely rocky. Is there life on any of them? We still have a lot more to
This sizzling world is so hot iron would
One of Kepler’s early discoveries was the small, scorched world of
With a year that lasts less than an Earth day and density high enough to
imply it’s probably made of iron and rock, this “lava world” gave us the first
solid evidence of a rocky planet outside our solar system.
If it’s not an alien megastructure, what
is this oddly fluctuating star?
When Kepler detected the oddly fluctuating light from
were born 11 billion years ago when our galaxy was in its youth. Imagine
what these ancient planets look like after all that time?
Kepler found a supernova exploding at
This premier planet hunter has also been watching stars explode. Kepler
recorded a sped-up version of a supernova called a
luminescent transit” that reached its peak brightness at breakneck
speed. It was caused by a star spewing out a dense shell of gas that lit up
when hit with the shockwave from the blast.