Our Eyes In The Sky See Toxic Waters

Which do you think you'll miss more after your first trip? Space when you're back on Earth or Earth when you're up in Space?

I think that I will miss space when I’m back on Earth. One astronaut when she returned said that gravity sucks, so I’m looking forward to finding out what that’s like.

13 Reasons to Have an Out of This World Friday (the 13th)

1. Know that not all of humanity is bound to the ground

Since 2000, the International Space Station has been continuously occupied by humans. There, crew members live and work while conducting important research that benefits life on Earth and will even help us eventually travel to deep space destinations, like Mars.

2. Smart people are up all night working in control rooms all over NASA to ensure that data keeps flowing from our satellites and spacecraft

Our satellites and spacecraft help scientists study Earth and space. Missions looking toward Earth provide information about clouds, oceans, land and ice. They also measure gases in the atmosphere, such as ozone and carbon dioxide, and the amount of energy that Earth absorbs and emits. And satellites monitor wildfires, volcanoes and their smoke.

Satellites and spacecraft that face toward space have a variety of jobs. Some watch for dangerous rays coming from the sun. Others explore asteroids and comets, the history of stars, and the origin of planets. Some fly near or orbit other planets. These spacecraft may look for evidence of water on Mars or capture close-up pictures of Saturn’s rings.

3. The spacecraft, rockets and systems developed to send astronauts to low-Earth orbit as part of our Commercial Crew Program is also helping us get to Mars

Changes to the human body during long-duration spaceflight are significant challenges to solve ahead of a mission to Mars and back. The space station allows us to perform long duration missions without leaving Earth’s orbit. 

Although they are orbiting Earth, space station astronauts spend months at a time in near-zero gravity, which allows scientists to study several physiological changes and test potential solutions. The more time they spend in space, the more helpful the station crew members can be to those on Earth assembling the plans to go to Mars.

4. Two new science missions will travel where no spacecraft has gone before…a Jupiter Trojan asteroid and a giant metal asteroid!

We’ve selected two missions that have the potential to open new windows on one of the earliest eras in the history of our solar system – a time less than 10 million years after the birth of our sun!

The first mission, Lucy, will visit six of Jupiter’s mysterious Trojan asteroids. The Trojans are thought to be relics of a much earlier era in the history of the solar system, and may have formed far beyond Jupiter’s current orbit.

The second mission, Psyche, will study a unique metal asteroid that’s never been visited before. This giant metal asteroid, known as 16 Psyche, is about three times farther away from the sun than is the Earth. Scientists wonder whether Psyche could be an exposed core of an early planet that could have been as large as Mars, but which lost its rocky outer layers due to a number of violent collisions billions of years ago.

5. Even astronauts eat their VEGGIES’s

NASA astronaut Shane Kimbrough collected the third and final harvest of the latest round of the Veggie investigation, testing the capability to grow fresh vegetables on the International Space Station. 

Understanding how plants respond to microgravity is an important step for future long-duration space missions, which will require crew members to grow their own food. Crew members have previously grown lettuce and flowers in the Veggie facility. This new series of the study expands on previous validation tests.

6. When you feel far away from home, you can think of the New Horizons spacecraft as it heads toward the Kuiper Belt, and the twin Voyager spacecraft are beyond the influence of our sun…billions of miles away 

Our New Horizons spacecraft completed its Pluto flyby in July 2015 and has continued on its way toward the Kuiper Belt. The spacecraft continues to send back important data as it travels toward deeper space at more than 32,000 miles per hour, and is nearly 3.2 billion miles from Earth.

In addition to New Horizons, our twin Voyager 1 and 2 spacecraft are exploring where nothing from Earth has flown before. Continuing on their more-than-37-year journey since their 1977 launches, they are each much farther away from Earth and the sun than Pluto. In August 2012, Voyager 1 made the historic entry into interstellar space, the region between the stars, filled with material ejected by the death of nearby stars millions of years ago.

7. Earth has a magnetic field that largely protects it from the solar wind stripping away out atmosphere…unlike Mars

Findings from our MAVEN mission have identified the process that appears to have played a key role in the transition of the Martian climate from an early, warm and wet environment to the cold, arid planet Mars is today. MAVEN data have enabled researchers to determine the rate at which the Martian atmosphere currently is losing gas to space via stripping by the solar wind. Luckily, Earth has a magnetic field that largely protects it from this process. 

8. There are humans brave enough to not only travel in space, but venture outside the space station to perform important repairs and updates during spacewalks

Spacewalks are important events where crew members repair, maintain and upgrade parts of the International Space Station. These activities can also be referred to as EVAs – Extravehicular Activities. Not only do spacewalks require an enormous amount of work to prepare for, but they are physically demanding on the astronauts. They are working in the vacuum of space in only their spacewalking suit. 

When on a spacewalk, astronauts use safety tethers to stay close to their spacecraft. One end of the tether is hooked to the spacewalker, while the other end is connected to the vehicle. Spacewalks typically last around 6.5 hours, but can be extended to 7 or 8 hours, if necessary.

9. We’re working to create new aircraft that will dramatically reduce fuel use, emissions and noise…meaning we could change the way you fly! 

The nation’s airlines could realize more than $250 billion dollars in savings in the near future thanks to green-related technologies that we are developing and refining. These new technologies could cut airline fuel use in half, pollution by 75% and noise to nearly one-eighth of today’s levels!

10. You can see a global image of your home planet…EVERY DAY

Once a day, we will post at least a dozen new color images of Earth acquired from 12 to 36 hours earlier. These images are taken by our EPIC camera from one million miles away on the Deep Space Climate Observatory (DSCOVR). Take a look HERE.

11. Employees of NASA have always been a mission driven bunch, who try to find answers that were previously unknown

The film “Hidden Figures,” focuses on the stories of Katherine Johnson, Mary Jackson and Dorothy Vaughan, African-American women who were essential to the success of early spaceflight. 

Today, we embrace their legacy and strive to include everyone who wants to participate in our ongoing exploration. In the 1960’s, we were on an ambitious journey to the moon, and the human computers portrayed in Hidden Figures helped get us there. Today, we are on an even more ambitious journey to Mars. We are building a vibrant, innovative workforce that reflects a vast diversity of discipline and thought, embracing and nurturing all the talent we have available, regardless of gender, race or other protected status. Take a look at our Modern Figures HERE.

12. A lot of NASA-developed tech has been transferred for use to the public 

Our Technology Transfer Program highlights technologies that were originally designed for our mission needs, but have since been introduced to the public market. HERE are a few spinoff technologies that you might not know about.

13. If all else fails, here’s an image of what we (Earth) and the moon look like from Mars  

From the most powerful telescope orbiting Mars comes a new view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon. The image combines two separate exposures taken on Nov. 20 by our High Resolution Imaging Science Experiment (HiRISE) camera on our Mars Reconnaissance Orbiter.

In the image, the reddish feature near the middle of the face of Earth is Australia.

Vote While You float: An Astronaut Voting Story

With the excitement of getting to the polls on Election Day many people will have a hard time keeping their feet on the ground, but astronauts who vote literally have to strap themselves down so they don’t float away.

Astronauts orbit the Earth at 17,000 miles per hour, but thanks to a bill passed by Texas legislatures in 1997 that put in place technical voting procedure for astronauts – nearly all of whom live in Texas – they also have the ability to vote from space!

Image Kjell Lindgren released on social media of the US flag floating in the Cupola module (11/12/2015) 

For astronauts, the voting process starts a year before launch, when astronauts are able to select which elections (local/state/federal) that they want to participate in while in space. Then, six months before the election, astronauts are provided with a standard form: the “Voter Registration and Absentee Ballot Request – Federal Post Card Application.”

 ‘Space voting’ was first used the same year it was implemented in 1997. NASA astronaut David Wolf became the first American to vote in space while on the Russian Mir Space Station. 

STS-86 crewmember David Wolf, the first American to vote in space, relaxes in the Spacehab module while Space Shuttle Atlantis was docked to Mir (10/16/1997) 

While astronauts don’t have to wait in line for his ballot like the rest of us, there is one disadvantage to voting in space: they miss out on the highly coveted “I Voted” sticker.

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Solar System: 10 Ways Interns Are Exploring Space With Us

Simulating alien worlds, designing spacecraft with origami and using tiny fossils to understand the lives of ancient organisms are all in a day’s work for interns at NASA.

Here’s how interns are taking our missions and science farther.

1. Connecting Satellites in Space

Becca Foust looks as if she’s literally in space – or, at least, on a sci-fi movie set. She’s surrounded by black, except for the brilliant white comet model suspended behind her. Beneath the socks she donned just for this purpose, the black floor reflects the scene like perfectly still water across a lake as she describes what happens here: “We have five spacecraft simulators that ‘fly’ in a specially designed flat-floor facility,” she says. “The spacecraft simulators use air bearings to lift the robots off the floor, kind of like a reverse air hockey table. The top part of the spacecraft simulators can move up and down and rotate all around in a similar way to real satellites.” It’s here, in this test bed on the Caltech campus, that Foust is testing an algorithm she’s developing to autonomously assemble and disassemble satellites in space. “I like to call it space K’nex, like the toys. We're using a bunch of component satellites and trying to figure out how to bring all of the pieces together and make them fit together in orbit,” she says. A NASA Space Technology Research Fellow, who splits her time between Caltech and NASA’s Jet Propulsion Laboratory (JPL), working with Soon-Jo Chung and Fred Hadaegh, respectively, Foust is currently earning her Ph.D. at the University of Illinois at Urbana-Champaign. She says of her fellowship, “I hope my research leads to smarter, more efficient satellite systems for in-space construction and assembly.”

2. Diving Deep on the Science of Alien Oceans

Three years ago, math and science were just subjects Kathy Vega taught her students as part of Teach for America. Vega, whose family emigrated from El Salvador, was the first in her family to go to college. She had always been interested in space and even dreamed about being an astronaut one day, but earned a degree in political science so she could get involved in issues affecting her community. But between teaching and encouraging her family to go into science, It was only a matter of time before she realized just how much she wanted to be in the STEM world herself. Now an intern at NASA JPL and in the middle of earning a second degree, this time in engineering physics, Vega is working on an experiment that will help scientists search for life beyond Earth. 

“My project is setting up an experiment to simulate possible ocean compositions that would exist on other worlds,” says Vega. Jupiter’s moon Europa and Saturn’s moon Enceladus, for example, are key targets in the search for life beyond Earth because they show evidence of global oceans and geologic activity. Those factors could allow life to thrive. JPL is already building a spacecraft designed to orbit Europa and planning for another to land on the icy moon’s surface. “Eventually, [this experiment] will help us prepare for the development of landers to go to Europa, Enceladus and another one of Saturn’s moons, Titan, to collect seismic measurements that we can compare to our simulated ones,” says Vega. “I feel as though I'm laying the foundation for these missions.”

3. Unfolding Views on Planets Beyond Our Solar System

“Origami is going to space now? This is amazing!” Chris Esquer-Rosas had been folding – and unfolding – origami since the fourth grade, carefully measuring the intricate patterns and angles produced by the folds and then creating new forms from what he’d learned. “Origami involves a lot of math. A lot of people don't realize that. But what actually goes into it is lots of geometric shapes and angles that you have to account for,” says Esquer-Rosas. Until three years ago, the computer engineering student at San Bernardino College had no idea that his origami hobby would turn into an internship opportunity at NASA JPL. That is, until his long-time friend, fellow origami artist and JPL intern Robert Salazar connected him with the Starshade project. Starshade has been proposed as a way to suppress starlight that would otherwise drown out the light from planets outside our solar system so we can characterize them and even find out if they’re likely to support life. Making that happen requires some heavy origami – unfurling a precisely-designed, sunflower-shaped structure the size of a baseball diamond from a package about half the size of a pitcher’s mound. It’s Esquer-Rosas’ project this summer to make sure Starshade’s “petals” unfurl without a hitch. Says Esquer-Rosas, “[The interns] are on the front lines of testing out the hardware and making sure everything works. I feel as though we're contributing a lot to how this thing is eventually going to deploy in space.”

4. Making Leaps in Extreme Robotics

Wheeled rovers may be the norm on Mars, but Sawyer Elliott thinks a different kind of rolling robot could be the Red Planet explorer of the future. This is Elliott’s second year as a fellow at NASA JPL, researching the use of a cube-shaped robot for maneuvering around extreme environments, like rocky slopes on Mars or places with very little gravity, like asteroids. A graduate student in aerospace engineering at Cornell University, Elliott spent his last stint at JPL developing and testing the feasibility of such a rover. “I started off working solely on the rover and looking at can we make this work in a real-world environment with actual gravity,” says Elliott. “It turns out we could.” So this summer, he’s been improving the controls that get it rolling or even hopping on command. In the future, Elliott hopes to keep his research rolling along as a fellow at JPL or another NASA center. “I'm only getting more and more interested as I go, so I guess that's a good sign,” he says.

5. Starting from the Ground Up

Before the countdown to launch or the assembling of parts or the gathering of mission scientists and engineers, there are people like Joshua Gaston who are helping turn what’s little more than an idea into something more. As an intern with NASA JPL’s project formulation team, Gaston is helping pave the way for a mission concept that aims to send dozens of tiny satellites, called CubeSats, beyond Earth’s gravity to other bodies in the solar system. “This is sort of like step one,” says Gaston. “We have this idea and we need to figure out how to make it happen.” Gaston’s role is to analyze whether various CubeSat models can be outfitted with the needed science instruments and still make weight. Mass is an important consideration in mission planning because it affects everything from the cost to the launch vehicle to the ability to launch at all. Gaston, an aerospace engineering student at Tuskegee University, says of his project, “It seems like a small role, but at the same time, it's kind of big. If you don't know where things are going to go on your spacecraft or you don't know how the spacecraft is going to look, it's hard to even get the proposal selected.”

6. Finding Life on the Rocks

By putting tiny samples of fossils barely visible to the human eye through a chemical process, a team of NASA JPL scientists is revealing details about organisms that left their mark on Earth billions of years ago. Now, they have set their sights on studying the first samples returned from Mars in the future. But searching for signatures of life in such a rare and limited resource means the team will have to get the most science they can out of the smallest sample possible. That’s where Amanda Allen, an intern working with the team in JPL’s Astrobiogeochemistry, or abcLab, comes in. “Using the current, state-of-the-art method, you need a sample that’s 10 times larger than we’re aiming for,” says Allen, an Earth science undergraduate at the University of California, San Diego, who is doing her fifth internship at JPL. “I’m trying to get a different method to work.” Allen, who was involved in theater and costume design before deciding to pursue Earth science, says her “superpower” has always been her ability to find things. “If there’s something cool to find on Mars related to astrobiology, I think I can help with that,” she says.

7. Taking Space Flight Farther

If everything goes as planned and a thruster like the one Camille V. Yoke is working on eventually helps send astronauts to Mars, she’ll probably be first in line to play the Mark Watney role. “I'm a fan of the Mark Watney style of life [in “The Martian”], where you're stranded on a planet somewhere and the only thing between you and death is your own ability to work through problems and engineer things on a shoestring,” says Yoke. A physics major at the University of South Carolina, Yoke is interning with a team that’s developing a next-generation electric thruster designed to accelerate spacecraft more efficiently through the solar system. “Today there was a brief period in which I knew something that nobody else on the planet knew – for 20 minutes before I went and told my boss,” says Yoke. “You feel like you're contributing when you know that you have discovered something new.”

8. Searching for Life Beyond Our Solar System

Without the option to travel thousands or even tens of light-years from Earth in a single lifetime, scientists hoping to discover signs of life on planets outside our solar system, called exoplanets, are instead creating their own right here on Earth. This is Tre’Shunda James’ second summer simulating alien worlds as an intern at NASA JPL. Using an algorithm developed by her mentor, Renyu Hu, James makes small changes to the atmospheric makeup of theoretical worlds and analyzes whether the combination creates a habitable environment. “This model is a theoretical basis that we can apply to many exoplanets that are discovered,” says James, a chemistry and physics major at Occidental College in Los Angeles. “In that way, it's really pushing the field forward in terms of finding out if life could exist on these planets.” James, who recently became a first-time co-author on a scientific paper about the team’s findings, says she feels as though she’s contributing to furthering the search for life beyond Earth while also bringing diversity to her field. “I feel like just being here, exploring this field, is pushing the boundaries, and I'm excited about that.”

9. Spinning Up a Mars Helicopter

Chloeleen Mena’s role on the Mars Helicopter project may be small, but so is the helicopter designed to make the first flight on the Red Planet. Mena, an electrical engineering student at Embry-Riddle Aeronautical University, started her NASA JPL internship just days after NASA announced that the helicopter, which had been in development at JPL for nearly five years, would be going to the Red Planet aboard the Mars 2020 rover. This summer, Mena is helping test a part needed to deploy the helicopter from the rover once it lands on Mars, as well as writing procedures for future tests. “Even though my tasks are relatively small, it's part of a bigger whole,” she says.

10. Preparing to See the Unseen on Jupiter's Moon Europa

In the 2020s, we’re planning to send a spacecraft to the next frontier in the search for life beyond Earth: Jupiter’s moon Europa. Swathed in ice that’s intersected by deep reddish gashes, Europa has unveiled intriguing clues about what might lie beneath its surface – including a global ocean that could be hospitable to life. Knowing for sure hinges on a radar instrument that will fly aboard the Europa Clipper orbiter to peer below the ice with a sort of X-ray vision and scout locations to set down a potential future lander. To make sure everything works as planned, NASA JPL intern Zachary Luppen is creating software to test key components of the radar instrument. “Whatever we need to do to make sure it operates perfectly during the mission,” says Luppen. In addition to helping things run smoothly, the astronomy and physics major says he hopes to play a role in answering one of humanity’s biggest questions. “Contributing to the mission is great in itself,” says Luppen. “But also just trying to make as many people aware as possible that this science is going on, that it's worth doing and worth finding out, especially if we were to eventually find life on Europa. That changes humanity forever!”

Read the full web version of this week’s ‘Solar System: 10 Things to Know” article HERE. 

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One Year of Leadership

It’s been one year since Jim Bridenstine was sworn in as our 13th administrator, starting the job on April 23, 2018. Since then, he has led the agency towards taking our nation farther than ever before — from assigning the first astronauts to fly on commercial vehicles to the International Space Station, to witnessing New Horizon’s arrival at the farthest object ever explored, to working to meet the challenge of landing humans on the lunar surface by 2024.

Here is a look at what happened in the last year under the Administrator’s leadership:

1. Assigned the first astronauts to fly on commercial spacecraft to the International Space Station.

Administrator Bridenstine introduced to the world on Aug. 3, 2018 the first U.S. astronauts who will fly on American-made, commercial spacecraft to and from the International Space Station — an endeavor that will return astronaut launches to U.S. soil for the first time since the space shuttle’s retirement in 2011.

“Today, our country’s dreams of greater achievements in space are within our grasp,” said Administrator Bridenstine. “This accomplished group of American astronauts, flying on new spacecraft developed by our commercial partners Boeing and SpaceX, will launch a new era of human spaceflight.”

2. Announced the first commercial effort to regularly send science payloads to the Moon.

Administrator Bridenstine announced new Moon partnerships with American companies — an important step to achieving long-term scientific study and human exploration of the Moon and Mars. Nine U.S. companies were named as eligible to bid on NASA delivery services to the Moon through Commercial Lunar Payload Services (CLPS) contracts on Nov. 29, 2018.  

3. Witnessed the teamwork that led to the latest mission to the Red Planet with Mars InSight’s landing.

On Nov. 26, 2018, the InSight lander successfully touched down on Mars after an almost seven-month, 300-million-mile (485-million-kilometer) journey from Earth. Administrator Bridenstine celebrated with the members of Mars Cube One and Mars InSight team members after the Mars lander successfully landed and began its mission to study the “inner space” of Mars: its crust, mantle and core.

"Today, we successfully landed on Mars for the eighth time in human history,” said NASA Administrator Jim Bridenstine. “InSight will study the interior of Mars, and will teach us valuable science as we prepare to send astronauts to the Moon and later to Mars…The best of NASA is yet to come, and it is coming soon.”

4. Oversaw the arrival of the first American mission to an asteroid designed to return samples and New Horizon’s arrival at Ultima Thule, the farthest object ever explored.

The spacecraft OSIRIS-REx traveled 1.4 million miles (2.2 million kilometers) to arrive at the asteroid Bennu on Dec. 3. The first asteroid sample mission is helping scientists investigate how planets formed and how life began, as well as improve our understanding of asteroids that could impact Earth. OSIRIS-Rex has already revealed water locked inside the clays that make up the asteroid.

And on the early hours of New Year’s Day, 2019, our New Horizons spacecraft flew past Ultima Thule in Kuiper belt, a region of primordial objects that hold keys to understanding the origins of the solar system.

“In addition to being the first to explore Pluto, today New Horizons flew by the most distant object ever visited by a spacecraft and became the first to directly explore an object that holds remnants from the birth of our solar system,” said Administrator Bridenstine. “This is what leadership in space is all about.”

5. Directed the first major milestone in commercial crew flights with the successful Space X Demo-1 mission.

Demonstration Mission-1 (Demo-1) was an uncrewed flight test designed to demonstrate a new commercial capability developed under NASA’s Commercial Crew Program. The mission began March 2, when the Crew Dragon launched from NASA’s Kennedy Space Center in Florida and docked to the International Space Station for five days.

“Today’s successful re-entry and recovery of the Crew Dragon capsule after its first mission to the International Space Station marked another important milestone in the future of human spaceflight,” said Administrator Bridenstine. “I want to once again congratulate the NASA and SpaceX teams on an incredible week. Our Commercial Crew Program is one step closer to launching American astronauts on American rockets from American soil.”

6. Is currently working to meet the challenge of advancing human exploration of the lunar surface to 2024.

Administrator Bridenstine has accomplished a lot since he swore in one year ago — but the best is yet to come. On March 26, Vice President Mike Pence tasked our agency with returning American astronauts to the Moon by 2024 at the fifth meeting of the National Space Council. 

“It is the right time for this challenge, and I assured the Vice President that we, the people of NASA, are up to the challenge,” said Administrator Bridenstine. “There’s a lot of excitement about our plans and also a lot of hard work and challenges ahead, but I know the NASA workforce and our partners are up to it.”

Learn more about what’s still to come this year at NASA:

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Hilary Swank cartwheeling through Mission Control >>>  the feel good content we’re looking for. 

To get some insight on playing an astronaut going to Mars, Hilary took a trip to Johnson Space Center and spoke with astronaut Jessica Meir who lived aboard the International Space Station for over 200 days!

Watch the duo talk about living in space, life on Earth after a mission and more! Check out her whole visit HERE: https://youtu.be/8NRJvUlpuKI

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I am interested in learning how to grow plants in space. How can I be involved in this as a college student, or independently?

Photograph of the Apollo 13 Spacecraft Being Returned to the Prime Recovery Ship, USS Iwo Jima, 4/17/1970

Series: Color Photograph Files, 1965 - 2002. Record Group 255: Records of the National Aeronautics and Space Administration, 1903 - 2006. 

Apollo 13 was intended to be the third Apollo mission to land on the Moon. The craft was launched from Kennedy Space Center in Merritt Island, Florida on April 11, 1970. Two days into the flight, damaged wire insulation inside the oxygen tank in the service module ignited, causing an explosion which vented the oxygen tank into space. Without oxygen, the service module became inoperable and the lunar mission quickly turned into a mission to safely return the crew to Earth. The astronauts worked with Mission Control to shut down the command module in order to conserve the remaining oxygen, forcing all three astronauts into the lunar module. The astronauts continued to work with Mission Control to combat one technical failure after another until, on April 17, 1970, the crew landed safely in the South Pacific Ocean.

source: phillyarchives.tumblr.com

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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Urban Growth of New Delhi

The capital of India, New Delhi, has been experiencing one of the fastest urban expansions in the world. Vast areas of croplands and grasslands are being turned into streets, buildings, and parking lots, attracting an unprecedented amount of new residents. By 2050, the United Nations projects India will add 400 million urban dwellers, which would be the largest urban migration in the world for the thirty-two year period.

These images show the growth in the city of New Delhi and its adjacent areas—a territory collectively known as Delhi—from December 5, 1989 to June 5, 2018. 

Most of the expansion in Delhi has occurred on the peripheries of New Delhi, as rural areas have become more urban. The geographic size of Delhi has almost doubled from 1991 to 2011, with the number of urban households doubling while the number of rural houses declined by half. Cities outside of Delhi—Bahadurgarh, Ghaziabad, Noida, Faridabad, and Gurugram—have also experienced urban growth over the past three decades, as shown in these images.

Read more: https://go.nasa.gov/2y32G7h

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