Saturn By Europeanspaceagency

How the New Horizon’s flyby changed the way we see Pluto 💓 [NASA/JPL] 

Discovery Shuttle docked to the ISS. 🌎🚀

Going the Distance... In Space

On April 17, NASA's New Horizons crossed a rare deep-space milestone – 50 astronomical units from the Sun, or 50 times farther from the Sun than Earth is. New Horizons is just the fifth spacecraft to reach this great distance, following the legendary Voyagers 1 and 2 and Pioneers 10 and 11. It’s almost 5 billion miles (7.5 billion kilometers) away; a remote region where a signal radioed from NASA's largest antennas on Earth, even traveling at the speed of light, needs seven hours to reach the far-flung spacecraft.

To celebrate reaching 50 AU, the New Horizons team compiled a list of 50 facts about the mission. Here are just a few of them; you'll find the full collection at: http://pluto.jhuapl.edu/News-Center/Fifty-Facts.php.

New Horizons is the first – and so far, only – spacecraft to visit Pluto. New Horizons sped through the Pluto system on July 14, 2015, providing a history-making close-up view of the dwarf planet and its family of five moons.

New Horizons is carrying some of the ashes of Pluto’s discoverer, Clyde Tombaugh. In 1930, the amateur astronomer spotted Pluto in a series of telescope images at Lowell Observatory in Arizona, making him the first American to discover a planet.

The “Pluto Not Yet Explored” U.S. stamp that New Horizons carries holds the Guinness World Record for the farthest traveled postage stamp. The stamp was part of a series created in 1991, when Pluto was the last unexplored planet in the solar system.

Dispatched at 36,400 miles per hour (58, 500 kilometers per hour) on January 19, 2006, New Horizons is still the fastest human-made object ever launched from Earth.

As the spacecraft flew by Jupiter’s moon Io, in February 2007, New Horizons captured the first detailed movie of a volcano erupting anywhere in the solar system except Earth.

New Horizons’ radioisotope thermoelectric generator (RTG) – its nuclear battery – will provide enough power to keep the spacecraft operating until the late-2030s.

Measurements of the universe’s darkness using New Horizons data found that the universe is twice as bright as predicted – a major extragalactic astronomy discovery!

New Horizons’ Venetia Burney Student Dust Counter is the first student-built instrument on any NASA planetary mission – and is providing unprecedented insight into the dust environment in the outer solar system.

New Horizons is so far away, that even the positons of the stars look different than what we see from Earth. This view of an "alien sky" allowed scientists to make stereo images of the nearest stars against the background of the galaxy.

Arrokoth – the official name the mission team proposed for the Kuiper Belt object New Horizons explored in January 2019 – is a Native American term that means “sky” in the Powhatan/Algonquin language.

Stay tuned in to the latest New Horizons updates on the mission website and follow NASA Solar System on Twitter and Facebook.

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Update your phones with our #CountdownToMars wallpapers, like this one, today: https://www.nasa.gov/feature/perseverance-mars-rover-wallpaper-images/

It's LANDING DAY for our Perseverance Mars Rover and her mission to search for ancient signs of life on the Red Planet!

Watch LIVE coverage today starting at 2:15pm ET (18:15 UTC):

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

Jupiter Descending 

 It was time for their close-up. Two days ago Jupiter and Saturn passed a tenth of a degree from each other in what is known a Great Conjunction. Although the two planets pass each other on the sky every 20 years, this was the closest pass in nearly four centuries. Taken early in day of the Great Conjunction, the featured multiple-exposure combination captures not only both giant planets in a single frame, but also Jupiter's four largest moons (left to right) Callisto, Ganymede, Io, and Europa -- and Saturn's largest moon Titan. 

Image Credit:  Damian Peach

Galilean moons

The Galilean moons are the four largest moons of Jupiter — Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in January 1610, and recognized by him as satellites of Jupiter in March 1610. They are the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with a radius larger than any of the dwarf planets. 

Io is the fourth largest moon in the Solar System. With over 400 active volcanos, Io is the most geologically active object in the Solar System. Its surface is dotted with more than 100 mountains, some of which are taller than Earth’s Mount Everest. Unlike most satellites in the outer Solar System (which have a thick coating of ice), Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Although not proven, recent data from the Galileo orbiter indicate that Io might have its own magnetic field.

Europa the second of the four Galilean moons, is the second closest to Jupiter and the smallest at 3121.6 kilometers in diameter, which is slightly smaller than the Moon. The name comes from a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete, though the name did not become widely used until the mid-20th century.  It has a smooth and bright surface, with a layer of water surrounding the mantle of the planet, thought to be 100 kilometers thick. The smooth surface includes a layer of ice, while the bottom of the ice is theorized to be liquid water. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life. 

Ganymede is the largest moon in the Solar System, and is even bigger than the planet Mercury. It is the only satellite in the Solar System known to possess a magnetosphere, likely created through convection within the liquid iron core. 

Callisto  is the fourth and last Galilean moon, and is the second largest of the four, and at 4820.6 kilometers in diameter, it is the third largest moon in the Solar System, and barely smaller than Mercury, though only a third of the latter’s mass. It is named after the Greek mythological nymph Callisto, a lover of Zeus who was a daughter of the Arkadian King Lykaon and a hunting companion of the goddess Artemis. It is one of the most heavily cratered satellites in the Solar System, and one major feature is a basin around 3000 km wide called Valhalla. 

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image credit: NASA/JPL

Saturn Aurora.

Credit: NASA, ESA, J Clarke and Z Levay

Our Amazing Solar System

Charon, moon of Pluto, observed by NASA’s New Horizons probe on this day in 2015.