2017 October 30

Two moons of Uranus: Titania and Oberon. Both moons were discovered by William Herschel in 1787.

Credit: NASA/JPL

evosia Chasing auroras is much like living life: if you show up, always be prepared for the amazing to happen.

The Daredevil Spacecraft That Will Touch the Sun

In the summer of 2018, we’re launching Parker Solar Probe, a spacecraft that will get closer to the Sun than any other in human history.

Parker Solar Probe will fly directly through the Sun’s atmosphere, called the corona. Getting better measurements of this region is key to understanding our Sun. For instance, the Sun releases a constant outflow of solar material, called the solar wind. We think the corona is where this solar wind is accelerated out into the solar system, and Parker Solar Probe’s measurements should help us pinpoint how that happens.  

The solar wind, along with other changing conditions on the Sun and in space, can affect Earth and are collectively known as space weather. Space weather can trigger auroras, create problems with satellites, cause power outages (in extreme cases), and disrupt our communications signals. That’s because space weather interacts with Earth’s upper atmosphere, where signals like radio and GPS travel from place to place.

Parker Solar Probe is named after pioneering physicist Gene Parker. In the 1950s, Parker proposed a number of concepts about how stars — including our Sun — give off energy. He called this cascade of energy the solar wind. Parker also theorized an explanation for the superheated solar atmosphere, the corona, which is hotter than the surface of the Sun itself.

Getting the answers to our questions about the solar wind and the Sun’s energetic particles is only possible by sending a probe right into the furnace of the Sun’s corona, where the spacecraft can reach 2,500 degrees Fahrenheit. Parker Solar Probe and its four suites of instruments – studying magnetic and electric fields, energetic particles, and the solar wind – will be protected from the Sun’s enormous heat by a 4.5-inch-thick carbon-composite heat shield.

Over the course of its seven-year mission, Parker Solar Probe will make two dozen close approaches to the Sun, continuously breaking its own records and sending back unprecedented science data.

Getting close to the Sun is harder than you might think, since the inertia of a spacecraft launched from Earth will naturally carry it in repeated orbits on roughly the same path. To nudge the orbit closer to the Sun on successive trips, Parker Solar Probe will use Venus’ gravity.

This is a technique called a gravity assist, and it’s been used by Voyager, Cassini, and OSIRIS-REx, among other missions. Though most missions use gravity assists to speed up, Parker Solar Probe is using Venus’ gravity to slow down. This will let the spacecraft fall deeper into the Sun’s gravity and get closer to our star than any other spacecraft in human history.

You can get a behind-the-scenes at Parker Solar Probe under construction in a clean room at facebook.com/NASASunScience today (Sept. 25) at 1:45 PM EDT.

Keep up with all the latest on Parker Solar Probe at nasa.gov/solarprobe or on Twitter @NASASun.

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The Heart Nebula or IC 1805, lies some 7500 light years away from Earth and is located in the Perseus Arm of the Galaxy in the constellation Cassiopeia. This is an emission nebula showing glowing ionized hydrogen gas and darker dust lanes. 

Image Credit: Simon Addis

Chasing the Shadow of Neptune’s Moon Triton

Our Flying Observatory

Our flying observatory, called SOFIA, carries a 100-inch telescope inside a Boeing 747SP aircraft. Scientists onboard study the life cycle of stars, planets (including the atmosphere of Mars and Jupiter), nearby planetary systems, galaxies, black holes and complex molecules in space.

AND in just a few days SOFIA is going on a special flight to chase the shadow of Neptune’s moon Triton as it crosses Earth’s surface!

In case you’re wondering, SOFIA stands for: Stratospheric Observatory for Infrared Astronomy.

Triton

Triton is 1,680 miles (2,700 km) across, making it the largest of the 13 moons orbiting Neptune. Unlike most large moons in our solar system, Triton orbits in the opposite direction of Neptune, called a retrograde orbit. This backward orbit leads scientists to believe that Triton formed in an area past Neptune, called the Kuiper Belt, and was pulled into its orbit around Neptune by gravity. 

The Voyager 2 spacecraft flew past Neptune and Triton in 1989 and found that Triton’s atmosphere is made up of mostly nitrogen…but it has not been studied in nearly 16 years!

Occultations are Eclipse-Like Events

An occultation occurs when an object, like a planet or a moon, passes in front of a star and completely blocks the light from that star. As the object blocks the star’s light, it casts a faint shadow on Earth’s surface. 

But unlike an eclipse, these shadows are not usually visible to the naked eye because the star and object are much smaller and not nearly as bright as our sun. Telescopes with special instruments can actually see these shadows and study the star’s light as it passes near and around the object – if they can be in the right place on Earth to catch the shadow.

Chasing Shadows

Scientists have been making advanced observations of Triton and a background star. They’ve calculated exactly where Triton’s faint shadow will fall on Earth! Our SOFIA team has designed a flight path that will put SOFIA (the telescope and aircraft) exactly in the center of the shadow at the precise moment that Triton and the star will align. 

This is no easy feat because the shadow is moving at more than 53,000 mph while SOFIA flies at Mach 0.85 (652 mph), so we only have about two minutes to catch the shadow!! But our SOFIA team has previously harnessed the aircraft’s mobility to study Pluto from inside the center of its occultation shadow, and is ready to do it again to study Triton!

What We Learn From Inside the Shadow

From inside the shadow, our team on SOFIA will study the star’s light as it passes around and through Triton’s atmosphere. This allows us to learn more about Triton’s atmosphere, including its temperature, pressure, density and composition! 

Our team will use this information to examine if Triton’s atmosphere has changed since our Voyager 2 spacecraft flew past it in 1989. That’s a lot of information from a bit of light inside a shadow! Similar observations of Uranus in 1977, from our previous flying observatory, led to the discovery of rings around that planet!

International Ground-Based Support

Ground-based telescopes across the United States and Europe – from Scotland to the Canary Islands – will also be studying Triton’s occultation. Even though most of these telescopes will not be in the center of the shadow, the simultaneous observations, from different locations on Earth, will give us information about how Triton’s atmosphere varies across its latitudes. 

This data from across the Earth and from onboard SOFIA will help researchers understand how Triton’s atmosphere is distorted at different locations by its high winds and its strong tides!

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

A slow-motion animation of the Crab Pulsar taken at 800 nm wavelength (near-infrared) using a Lucky Imaging camera from Cambridge University, showing the bright pulse and fainter interpulse.

Credit: Cambridge University Lucky Imaging Group

When a star more massive than our sun reaches the end of its life cycle, it goes in a spectacular blaze of glory known as a supernova. This explosion indicates that the star is dunzo, dead, or whatever we call it in the parlance of our times. But a new study found that one unusual star zombie-Jon-Snowed itself and as an astronomer tells Inverse, no one knows quite how.

Messier 82

Messier 82 is a starburst galaxy about 12 million light-years away in the constellation Ursa Major. A member of the M81 Group, it is about five times more luminous than the whole Milky Way and has a center one hundred times more luminous than our galaxy’s center.

Image credit: NASA/ESA & Hubble

The Extraordinary Core of a Neutron Star

Lucy Reading-Ikkanda/Quanta Magazine; Source: Feryal Özel