One hundred years ago this month, Albert Einstein published his theory of general relativity (GR), one of the most important scientific achievements in the last century.
A key result of Einstein’s theory is that matter warps space-time, and thus a massive object can cause an observable bending of light from a background object. The first success of the theory was the observation, during a solar eclipse, that light from a distant background star was deflected by the predicted amount as it passed near the sun.
When Einstein developed the general theory of relativity, he was trying to improve our understanding of how the universe works. At the time, Newtonian gravity was more than sufficient for any practical gravity calculations. However, as often happens in physics, general relativity has applications that would not have been foreseen by Einstein or his contemporaries.
How many of us have used a smartphone to get directions? Or to tag our location on social media? Or to find a recommendation for a nearby restaurant? These activities depend on GPS. GPS uses radio signals from a network of satellites orbiting Earth at an altitude of 20,000 km to pinpoint the location of a GPS receiver. The accuracy of GPS positioning depends on precision in time measurements of billionths of a second. To achieve such timing precision, however, relativity must be taken into account.
Our Gravity Probe B (GP-B) mission has confirmed two key predictions derived from Albert Einstein’s general theory of relativity, which the spacecraft was designed to test. The experiment, launched in 2004, and measured the warping of space and time around a gravitational body, and frame-dragging, the amount a spinning object pulls space and time with it as it rotates.
Scientists continue to look for cracks in the theory, testing general relativity predictions using laboratory experiments and astronomical observations. For the past century, Einstein’s theory of gravity has passed every hurdle.
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Billions of years ago, Mars was a very different world. Liquid water flowed in long rivers that emptied into lakes and shallow seas. A thick atmosphere blanketed the planet and kept it warm.
Today, Mars is bitter cold. The Red Planet’s thin and wispy atmosphere provides scant cover for the surface below.
The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission is part of our Mars Scout program. This spacecraft launched in November 2013, and is exploring the Red Planet’s upper atmosphere, ionosphere and interactions with the sun and solar wind.
The purpose of the MAVEN mission is to determine the state of the upper atmosphere of Mars, the processes that control it and the overall atmospheric loss that is currently occurring. Specifically, MAVEN is exploring the processes through which the top of the Martian atmosphere can be lost to space. Scientists think that this loss could be important in explaining the changes in the climate of Mars that have occurred over the last four billion years.
New Findings
Today, Nov. 5, we will share new details of key science findings from our ongoing exploration of Mars during a news briefing at 2 p.m. EDT. This event will be broadcast live on NASA Television. Have questions? Use #askNASA during the briefing.
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Appearing like a winged creature poised on a pedestal, this object is actually a billowing tower of cold gas and dust rising from a stellar nursery called the Eagle Nebula. The soaring tower is 9.5 light-years high, about twice the distance from our Sun to the next nearest star
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Milky Way over Spencer Bay, Moosehead Lake, Maine
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We’ve taken 10 of our top Instagram posts and put them here for your viewing pleasure. Now, your next 10 cell phone backgrounds can be found in one place.
10. Water on Mars
With 210,000 likes, this image is a favorite on Instagram. New findings from our Mars Reconnaissance Orbiter (MRO) provide the strongest evidence yet that liquid water flows intermittently on present-day Mars. Dark, narrow streaks on Martian slopes such as these at Hale Crater are inferred to be formed by seasonal flow of water on contemporary Mars. The streaks are roughly the length of a football field.
9. Smoke Ring for a Halo
With 210,000 likes, this image shined on Instagram. Two stars shine through the center of a ring of cascading dust in this image taken by the Hubble Space Telescope. The star system is named DI Cha, and while only two stars are apparent, it is actually a quadruple system containing two sets of binary stars. As this is a relatively young star system it is surrounded by dust.
8. Pluto’s Largest Moon, Charon
With 216,000 likes, a lot of people thought this image was interesting on Instagram. Our New Horizons spacecraft has returned the best color and the highest resolution images yet of Pluto’s largest moon, Charon - and these pictures show a surprisingly complex and violent history. This high-resolution enhanced color view of Charon was captured just before closest approach on July 14. The image combines blue, red and infrared images; the colors are processed to best highlight the variation of surface properties across Charon.
7. Veil Nebula
With 220,000 likes, many people favorited this image on Instagram. This is the expanding remains of a massive star that exploded about 8,000 years ago. This view is a mosaic of six pictures from our Hubble Space Telescope of a small area roughly two light-years across, covering only a tiny fraction of the nebula’s vast structure. This close-up look unveils wisps of gas, which are all that remain of what was once a star 20 times more massive than our sun.
6. Messier 94 Galaxy
With 234,000 likes, this image is a favorite on Instagram. This image shows the galaxy Messier 94, which lies in the small northern constellation of the Hunting Dogs, about 16 million light-years away. Within the bright ring or starburst ring around Messier 94, new stars are forming at a high rate and many young, bright stars are present within it.
5. Solar ‘Pumpkin’
With 247,000 likes, many followers enjoyed this image on Instagram. This photo was posted on Halloween and shows active regions on the sun combined to look something like a jack-o-lantern’s face. The image was captured by NASA’s Solar Dynamics Observatory in October 2014, which watches the sun at all times from its orbit in space.
4. Italy from the International Space Station
With 251,000 likes, this image captivated many of you on Instagram. Before drifting off to sleep, NASA astronaut Scott Kelly (@stationcdrkelly) captured this images from the International Space Station and wrote, “ Day 180. Moonlight over Italy. #BuonaNotte Good night from @ISS! #YearInSpace.”
3. Cosmic Archaeological Dig
With 286,000 likes, this image dazzled many of you on Instagram. Peering deep into the Milky Way’s crowded central hub of stars, researchers using our Hubble Space Telescope have uncovered for the first time a population of ancient white dwarfs – smoldering remnants of once-vibrant stars that inhabited the core. Finding these relics at last can yield clues to how our galaxy was built, long before Earth and our sun formed. This image is a small section of Hubble’s view of the dense collection of stars crammed together in the galactic bulge.
2. Super Blood Moon
With 310,000 likes, this image was very popular on Instagram. It shows the Super Blood Moon behind the Washington Monument on Sunday, Sept. 27, in Washington, DC. The combination of a supermoon and total lunar eclipse last occurred in 1982 and will not happen again until 2033.
1. Pluto
With 363,000 likes, this image is one of our most popular pictures on Instagram. The dwarf planet sent a love note back to Earth via our New Horizons spacecraft, which traveled more than 9 years and 3+ billion miles. This was the last and most detailed image of Pluto sent to Earth before the moment of closest approach, which was at 7:49 a.m. EDT Tuesday, July 14 - about 7,750 miles above the surface – roughly the same distance from New York to Mumbai, India - making it the first-ever space mission to explore a world so far from Earth.
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The sun is a star, a hot ball of glowing gases at the heart of our solar system. Its influence extends far beyond the orbits of distant Neptune and Pluto. Without the sun’s intense energy and heat, there would be no life on Earth. And though it is special to us, there are billions of stars like our sun scattered across the Milky Way galaxy.
If the sun were as tall as a typical front door, the Earth would be the size of a U.S. nickel
The temperature at the sun’s core is about 27 million degrees Fahrenheit
Our sun is more massive than the average star in its neighborhood. Nearly 90% of stars are less massive, making them cooler and dimmer
The sun contains 99.9% of all matter in our solar system
During a single second, the sun converts 4 million tons of matter to pure energy
It would take about 1 million Earths to fill the sun if it were a hollow ball
The sun rotates on its axis approximately once every 27 days
The sun is 93 million miles away from Earth and is almost 5 billion years old
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