At the end of 2018, the cosmic ray subsystem (CRS) aboard NASA's Voyager 2 spacecraft provided evidence that Voyager 2 had left the heliosphere (the plasma bubble the Sun blows around itself). There were steep drops in the rate at which particles that originate inside the heliosphere hit the instrument's radiation detector. At the same time, there were significant increases in the rate at which particles that originate outside our heliosphere (also known as galactic cosmic rays) hit the detector. The graphs show data from Voyager 2's CRS, which averages the number of particle hits over a six-hour block of time. CRS detects both lower-energy particles that originate inside the heliosphere (greater than 0.5 MeV) and higher-energy particles that originate farther out in the galaxy (greater than 70 MeV). https://photojournal.jpl.nasa.gov/catalog/PIA22924

These graphs compare data from identical instruments onboard NASA's Voyager 1 and Voyager 2 spacecraft as they each exited the heliosphere. Voyager 1 exited in 2012, and Voyager 2 exited in 2018. The cosmic ray subsystem (CRS) measures the rate of energetic particles hitting the radiation detector on the instrument. The top graph shows high energy particles (called cosmic rays) that originate outside the heliosphere. The CRS instruments on both spacecraft observed similar, but not identical, increases in the cosmic ray rate as they both crossed the heliopause (the outer edge of the heliosphere). The lower graph shows slightly lower energy particles that originate inside the heliosphere. Both spacecraft detected a similar but not identical decrease in these lower energy particles when they crossed the heliopause and immediately after. https://photojournal.jpl.nasa.gov/catalog/PIA22916

This graphic shows the position of the Voyager 1 and Voyager 2 probes, relative to the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Voyager 1 crossed the heliopause, or the edge of the heliosphere, in 2012. Voyager 2 is still in the heliosheath, or the outermost part of the heliosphere. https://photojournal.jpl.nasa.gov/catalog/PIA22566

This illustration of NASA's Voyager 2 spacecraft shows the location of the onboard science instruments that are still operating: the magnetometer, the cosmic ray subsystem, the plasma science experiment, the low-energy charged particle instrument and the antennas used by the plasma wave subsystem. https://photojournal.jpl.nasa.gov/catalog/PIA22915

This artist concept of NASA Voyager spacecraft with its antennapointing to Earth.

The set of graphs on the left illustrates the drop in electrical current detected in three directions by Voyager 2's plasma science experiment (PLS) to background levels. They are among the key pieces of data that Voyager scientists used to determine that Voyager 2 entered interstellar space, the space between stars, in November 2018. The disappearance in electrical current in the sunward-looking detectors indicates the spacecraft is no longer in the outward flow of solar wind plasma. It is instead in a new plasma environment -- interstellar medium plasma. The image on the right shows the Faraday cups of the PLS. The three sunward pointed cups point in slightly different directions in order to measure the direction of the solar wind. The fourth cup (on the upper left) points perpendicular to the others. https://photojournal.jpl.nasa.gov/catalog/PIA22922

This set of graphs illustrates how data from two key instruments point to NASA's Voyager 2 spacecraft entering interstellar space, or the space between the stars, in November 2018. The top two plots come from the plasma science experiment (PLS). The plasma -- or ionized gas -- of interstellar space is significantly denser than the plasma inside the bubble of plasma the Sun blows around itself (the heliosphere). There is a jump on the graph in November 2018. At the same time, the measurements show that the outward speed (radial velocity) of the plasma the Sun is blowing (also known as the solar wind) sharply decreased. The bottom two plots come from the cosmic ray subsystem, which counts hits per second of higher-energy particles that originate from outside the solar bubble and lower-energy particles that originate from inside the solar bubble. The outsideparticles (also known as galactic cosmic rays or GCRs) increased and the inside particles (greater than 0.5 MeV) decreased at the same time the plasma science instrument detected its changes. The horizontal axis proceeds according to the numbered days of the year in 2018. https://photojournal.jpl.nasa.gov/catalog/PIA22923

This illustration shows the position of NASA's Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Voyager 1 crossed the heliopause, or the edge of the heliosphere, in August 2012. Heading in a different direction, Voyager 2 crossed another part of the heliopause in November 2018. https://photojournal.jpl.nasa.gov/catalog/PIA22835

This artist's concept puts solar system distances -- and the travels of NASA's Voyager 2 spacecraft -- in perspective. The scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the Sun to Earth, which is about 93 million miles, or 150 million kilometers. Neptune, the most distant planet from the Sun, is about 30 AU. Much of the solar system is actually in interstellar space. Informally, the term "solar system" is often used to mean the space out to the last planet. Scientific consensus, however, says the solar system goes out to the Oort Cloud, the source of the comets that swing by our sun on long time scales. Beyond the outer edge of the Oort Cloud, the gravity of other stars begins to dominate that of the Sun. The inner edge of the main part of the Oort Cloud could be as close as 1,000 AU from our Sun. The outer edge is estimated to be around 100,000 AU. Voyager 2, the second farthest human-made object after Voyager 1, is around 119 AU from the Sun. Indications from the scientific instruments suggest Voyager 2 passed beyond our heliosphere (the bubble of plasma the Sun blows around itself) and into interstellar space (the space between stars) in November 2018. The heliosphere has a turbulent outer boundary known as the heliosheath. The termination shock is the inner boundary of the heliosheath and the heliopause is the outer boundary, beyond which lies interstellar space. Voyager 2 crossed the termination shock at 84 AU in August 2007. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Voyager 2 is heading away from the Sun about 36 degrees out of the ecliptic plane (plane of the planets) to the south, toward the constellations of Sagittarius and Pavo. In about 40,000 years, Voyager 2 will be closer to another star than our own Sun, coming within about 1.7 light years of a star called Ross 248, a small star in the constellation of Andromeda. https://photojournal.jpl.nasa.gov/catalog/PIA22921

Gary Flandro, Voyager mission grand tour creator, speaks on a panel at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Gary Flandro, Voyager mission grand tour creator, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Ed Stone, Voyager project scientist, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Suzy Dodd, Voyager project manager, NASA's Jet Propulsion Laboratory, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Ann Druyan, writer/producer and golden record visionary, speaks about the last image of Earth from the Voyager spacecraft, at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Ed Stone, Voyager project scientist, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Alan Cummings, Voyager researcher, Caltech, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, gives opening remarks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, is interviewed prior to serving on a panel at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, gives opening remarks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, gives opening remarks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, gives opening remarks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, speaks on a panel at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

NASA's twin Voyager spacecraft, launched in 1977, are traveling through interstellar space at around 35,000 mph (56,000 kph). This artist's concept depicts one of the probes speeding away. The Voyager spacecraft were built by NASA's Jet Propulsion Laboratory, which continues to operate both. JPL is a division of Caltech in Pasadena, California. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the agency's Science Mission Directorate in Washington. For more information about the Voyager spacecraft, visit https://science.nasa.gov/mission/voyager/. https://photojournal.jpl.nasa.gov/catalog/PIA26353

Ann Druyan, writer/producer and golden record visionary, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Ann Druyan, writer/producer and golden record visionary, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

An audience member asks a question at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Gary Knell, President and CEO of National Geographic Society, gives opening remarks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Ann Druyan, writer/producer and golden record visionary, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Ann Druyan, writer/producer and golden record visionary, speaks on a panel at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Morgan Cable, researcher, NASA's Jet Propulsion Laboratory, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Eric Zirnstein, researcher, Princeton University, speaks at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Ann Druyan, writer/producer and golden record visionary, speaks on a panel with moderator Victoria Jaggard, National Geographic Magazine science editor, left, Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, right; and Ed Stone, Voyager project scientist, not pictured, at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Ed Stone, Voyager project scientist, right, speaks on a panel with Thomas Zurbuchen, NASA associate administrator, Science Mission Directorate, left, at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Matthew Shindell, curator, Smithsonian National Air and Space Museum (NASM), far left, moderates a panel including, from left to right, Ed Stone, Voyager project scientist; Gary Flandro, Voyager mission grand tour creator; Alan Cummings, Voyager researcher; Suzy Dodd, Voyager project manager, NASA's Jet Propulsion Laboratory; and Ann Druyan, writer/producer, Golden Record Visionary during a celebration of the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at NASM in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Matthew Shindell, curator, Smithsonian National Air and Space Museum (NASM), far left, moderates a panel including, from left to right, Ed Stone, Voyager project scientist; Gary Flandro, Voyager mission grand tour creator; Alan Cummings, Voyager researcher; Suzy Dodd, Voyager project manager, NASA's Jet Propulsion Laboratory; and Ann Druyan, writer/producer, Golden Record Visionary during a celebration of the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at NASM in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

William Shatner of Star Trek, is seen on a live feed from NASA's Jet Propulsion Laboratory, giving the order to send a message into deep space, during an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at Smithsonian's National Air and Space Museum in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey

Panelists, from left to right, Ed Stone, Voyager project scientist; Victoria Jaggard, National Geographic Magazine science editor and moderator for the panel; Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate; and Ann Druyan, writer/producer and golden record visionary, visit in the green room before speaking at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Victoria Jaggard, National Geographic Magazine science editor, left, moderates a panel discussion with, Ann Druyan, writer/producer and golden record visionary, second from left; Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, second from right; and Ed Stone, Voyager project scientist, right, at an event to celebrate the 40th Anniversary of the launch of the Voyager 1 and 2 missions, Tuesday, September 5, 2017 at National Geographic Society Headquarters in Washington. Voyager 1 was launched September 5, 1977, with a mission to study Jupiter and Saturn, but now the twin Voyager spacecrafts are on a journey into interstellar space to search for the heliopause, a region never reached by any other spacecraft. Photo Credit: (NASA/Aubrey Gemignani)

Dwayne Brown, Senior Public Affairs Officer, NASA Science Mission Directorate at NASA Headquarters, kicks off a news conference on NASA's Voyager 1 spacecraft, Thursday, Sept. 12, 2013 in Washington. NASA's Voyager 1 spacecraft officially is the first human-made object to venture into interstellar space. The 36-year-old probe is about 12 billion miles (19 billion kilometers) from our sun. New and unexpected data indicate Voyager 1 has been traveling for about one year through plasma, or ionized gas, present in the space between stars. A report on the analysis of this new data is published in Thursday's edition of the journal Science. Photo Credit: (NASA/Carla Cioffi)

This artist's concept puts solar system distances in perspective. The scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the sun to the Earth, which is about 93 million miles or 150 million kilometers. Neptune, the most distant planet from the sun, is about 30 AU. Informally, the term &quot;solar system&quot; is often used to mean the space out to the last planet. Scientific consensus, however, says the solar system goes out to the Oort Cloud, the source of the comets that swing by our sun on long time scales. Beyond the outer edge of the Oort Cloud, the gravity of other stars begins to dominate that of the sun. The inner edge of the main part of the Oort Cloud could be as close as 1,000 AU from our sun. The outer edge is estimated to be around 100,000 AU. NASA's Voyager 1, humankind's most distant spacecraft, is around 125 AU. Scientists believe it entered interstellar space, or the space between stars, on Aug. 25, 2012. Much of interstellar space is actually inside our solar system. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Alpha Centauri is currently the closest star to our solar system. But, in 40,000 years, Voyager 1 will be closer to the star AC +79 3888 than to our own sun. AC +79 3888 is actually traveling faster toward Voyager 1 than the spacecraft is traveling toward it. The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory, in Pasadena, Calif. Caltech manages JPL for NASA. The Voyager missions are a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate at NASA Headquarters in Washington. For more information about Voyager, visit: <a href="http://www.nasa.gov/voyager" rel="nofollow">www.nasa.gov/voyager</a> and <a href="http://voyager.jpl.nasa.gov" rel="nofollow">voyager.jpl.nasa.gov</a> . Image credit: NASA/JPL-Caltech <b><a href="http://www.nasa.gov/audience/formedia/features/MP_Photo_Guidelines.html" rel="nofollow">NASA image use policy.</a></b> <b><a href="http://www.nasa.gov/centers/goddard/home/index.html" rel="nofollow">NASA Goddard Space Flight Center</a></b> enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. <b>Follow us on <a href="http://twitter.com/NASAGoddardPix" rel="nofollow">Twitter</a></b> <b>Like us on <a href="http://www.facebook.com/pages/Greenbelt-MD/NASA-Goddard/395013845897?ref=tsd" rel="nofollow">Facebook</a></b> <b>Find us on <a href="http://instagram.com/nasagoddard?vm=grid" rel="nofollow">Instagram</a></b>

The International Astronomical Union (IAU), the internationally recognized authority for naming celestial bodies and their surface features, approved names of 14 surface features on Pluto in August 2017. The names were proposed by NASA's New Horizons team following the first reconnaissance of Pluto and its moons by the New Horizons spacecraft in 2015. The names, listed below, pay homage to the underworld mythology, pioneering space missions, historic pioneers who crossed new horizons in exploration, and scientists and engineers associated with Pluto and the Kuiper Belt. Tombaugh Regio honors Clyde Tombaugh (1906-1997), the U.S. astronomer who discovered Pluto in 1930 from Lowell Observatory in Arizona. Burney crater honors Venetia Burney (1918-2009), who as an 11-year-old schoolgirl suggested the name "Pluto" for Clyde Tombaugh's newly discovered planet. Later in life she taught mathematics and economics. Sputnik Planitia is a large plain named for Sputnik 1, the first space satellite, launched by the Soviet Union in 1957. Tenzing Montes and Hillary Montes are mountain ranges honoring Tenzing Norgay (1914-1986) and Sir Edmund Hillary (1919-2008), the Indian/Nepali Sherpa and New Zealand mountaineer were the first to reach the summit of Mount Everest and return safely. Al-Idrisi Montes honors Ash-Sharif al-Idrisi (1100-1165/66), a noted Arab mapmaker and geographer whose landmark work of medieval geography is sometimes translated as "The Pleasure of Him Who Longs to Cross the Horizons.” Djanggawul Fossae defines a network of long, narrow depressions named for the Djanggawuls, three ancestral beings in indigenous Australian mythology who traveled between the island of the dead and Australia, creating the landscape and filling it with vegetation. Sleipnir Fossa is named for the powerful, eight-legged horse of Norse mythology that carried the god Odin into the underworld. Virgil Fossae honors Virgil, one of the greatest Roman poets and Dante's fictional guide through hell and purgatory in the Divine Comedy. Adlivun Cavus is a deep depression named for Adlivun, the underworld in Inuit mythology. Hayabusa Terra is a large land mass saluting the Japanese spacecraft and mission (2003-2010) that performed the first asteroid sample return. Voyager Terra honors the pair of NASA spacecraft, launched in 1977, that performed the first "grand tour" of all four giant planets. The Voyager spacecraft are now probing the boundary between the Sun and interstellar space. Tartarus Dorsa is a ridge named for Tartarus, the deepest, darkest pit of the underworld in Greek mythology. Elliot crater recognizes James Elliot (1943-2011), an MIT researcher who pioneered the use of stellar occultations to study the solar system -- leading to discoveries such as the rings of Uranus and the first detection of Pluto's thin atmosphere. https://photojournal.jpl.nasa.gov/catalog/PIA21944

NASA's Europa Clipper spacecraft will carry a special message when it launches in October 2024 and heads toward Jupiter's moon Europa. The moon shows strong evidence of an ocean under its icy crust, with more than twice the amount of water of all of Earth's oceans combined. A triangular metal plate, seen here, will honor that connection to Earth. The plate is made of tantalum metal and is about 7 by 11 inches (18 by 28 centimeters). Engraved on both sides, it seals an opening in the electronics vault, which houses the spacecraft's sensitive electronics. The side shown here features U.S. Poet Laureate Ada Limón's handwritten "In Praise of Mystery: A Poem for Europa," and will be affixed with a silicon microchip stenciled with more than 2.6 million names submitted by the public. The microchip will be placed at the center of the illustration of a bottle amid the Jovian system – a reference to NASA's "Message in a Bottle" campaign, which invited the public to send their names with the spacecraft. The artwork includes the Drake Equation, which was formulated by astronomer Frank Drake in 1961 to estimate the possibility of finding advanced civilizations beyond Earth. Also featured is a reference to the radio frequencies considered plausible for interstellar communication, symbolizing how humanity uses this radio band to listen for messages from the cosmos. These particular frequencies match the radio waves emitted in space by the components of water and are known by astronomers as the "water hole." On the plate, they are depicted as radio emission lines. The plate includes a portrait of one of the founders of planetary science, Ron Greeley, whose early efforts to develop a Europa mission two decades ago laid the foundation for Europa Clipper. In the spirit of the Voyager spacecraft's Golden Record, which carries sounds and images to convey the richness and diversity of life on Earth, the layered message on Europa Clipper aims to spark the imagination and offer a unifying vision. Europa Clipper, set to launch from Kennedy Space Center in Florida, will arrive at the Jupiter system in 2030 and conduct about 50 flybys of the moon Europa. The mission's main science goal is to determine whether there are places below Europa, that could support life. The mission's three main science objectives are to determine the thickness of the moon's icy shell and its surface interactions with the ocean below, to investigate its composition, and to characterize its geology. The mission's detailed exploration of Europa will help scientists better understand the astrobiological potential for habitable worlds beyond our planet. https://photojournal.jpl.nasa.gov/catalog/PIA26062