Celebrating 17 Years Of NASA’s ‘Little Earth Satellite That Could’

I just watched the 4 clearly visible planets march across the sky with the moon in the center, so here’s a short guide to the night sky as the last 3 move across.

mammenxTime lapse of the milky way rolling across the night sky, flanked by the planets Jupiter, Saturn & Mars. Taken from Diskit Ladakh, this place truly has some fantastic unobstructed views of the night sky

Cassini's Final Image of Saturn

Here's a mosaic of Saturn made from raw images acquired by Cassini on Sept. 13, 2017, as it was on its way toward its dive into the planet's atmosphere. These images are uncalibrated for color but were acquired in visible-light RGB filters. This will be our last close-up image of Saturn for a long time. Credit: NASA/JPL-Caltech/Space Science Institute/Jason Major

The last look before her descent in fire…

Five Famous Pulsars from the Past 50 Years

Early astronomers faced an obstacle: their technology. These great minds only had access to telescopes that revealed celestial bodies shining in visible light. Later, with the development of new detectors, scientists opened their eyes to other types of light like radio waves and X-rays. They realized cosmic objects look very different when viewed in these additional wavelengths. Pulsars — rapidly spinning stellar corpses that appear to pulse at us — are a perfect example.

The first pulsar was observed 50 years ago on August 6, 1967, using radio waves, but since then we have studied them in nearly all wavelengths of light, including X-rays and gamma rays.

Typical Pulsar

Most pulsars form when a star — between 8 and 20 times the mass of our sun — runs out of fuel and its core collapses into a super dense and compact object: a neutron star. 

These neutron stars are about the size of a city and can rotate slowly or quite quickly, spinning anywhere from once every few hours to hundreds of times per second. As they whirl, they emit beams of light that appear to blink at us from space.

First Pulsar

One day five decades ago, a graduate student at the University of Cambridge, England, named Jocelyn Bell was poring over the data from her radio telescope - 120 meters of paper recordings.

Image Credit: Sumit Sijher

She noticed some unusual markings, which she called “scruff,” indicating a mysterious object (simulated above) that flashed without fail every 1.33730 seconds. This was the very first pulsar discovered, known today as PSR B1919+21.

Best Known Pulsar

Before long, we realized pulsars were far more complicated than first meets the eye — they produce many kinds of light, not only radio waves. Take our galaxy’s Crab Nebula, just 6,500 light years away and somewhat of a local celebrity. It formed after a supernova explosion, which crushed the parent star’s core into a neutron star. 

The resulting pulsar, nestled inside the nebula that resulted from the supernova explosion, is among the most well-studied objects in our cosmos. It’s pictured above in X-ray light, but it shines across almost the entire electromagnetic spectrum, from radio waves to gamma rays.

Brightest Gamma-ray Pulsar

Speaking of gamma rays, in 2015 our Fermi Gamma-ray Space Telescope discovered the first pulsar beyond our own galaxy capable of producing such high-energy emissions. 

Located in the Tarantula Nebula 163,000 light-years away, PSR J0540-6919 gleams nearly 20 times brighter in gamma-rays than the pulsar embedded in the Crab Nebula.

Dual Personality Pulsar

No two pulsars are exactly alike, and in 2013 an especially fast-spinning one had an identity crisis. A fleet of orbiting X-ray telescopes, including our Swift and Chandra observatories, caught IGR J18245-2452 as it alternated between generating X-rays and radio waves. 

Scientists suspect these radical changes could be due to the rise and fall of gas streaming onto the pulsar from its companion star.

Transformer Pulsar

This just goes to show that pulsars are easily influenced by their surroundings. That same year, our Fermi Gamma Ray Space Telescope uncovered another pulsar, PSR J1023+0038, in the act of a major transformation — also under the influence of its nearby companion star. 

The radio beacon disappeared and the pulsar brightened fivefold in gamma rays, as if someone had flipped a switch to increase the energy of the system. 

NICER Mission

Our Neutron star Interior Composition Explorer (NICER) mission, launched this past June, will study pulsars like those above using X-ray measurements.

With NICER’s help, scientists will be able to gaze even deeper into the cores of these dense and mysterious entities.

For more information about NICER, visit https://www.nasa.gov/nicer

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

Black Holes Are Real And Spectacular, And So Are Their Event Horizons

“Originally estimated to be slightly larger than its M87 counterpart, the black hole at the center of the Milky Way — known as Sagittarius A* — has not yet had its event horizon imaged. When you observe the Universe, you don’t always get what you expect; sometimes, you get what it gives you. Instead, it was M87’s black hole that came through first, which was a much brighter and a much cleaner signal.

What we’ve found is spectacular. Those dark pixels at the center of the image are actually the silhouette of the event horizon itself. The light that we observe comes from the accelerated, heated matter around it, which must emit electromagnetic radiation. Where the matter exists, it emits radio waves, and the dark circle we see is where the background radio waves are blocked by the event horizon itself.”

We have an event horizon, folks! It wasn’t the one at the center of our galaxy that came through first, but rather the one at the center of Messier 87: a black hole over 1,000 times more massive, but some 2,000 times farther away, than the one contained in the Milky Way. This is an ultramassive black hole that’s almost the size of the entire Solar System, and its event horizon is real.

Come get the full story on what we know, now that we have our image, about black holes in the aftermath of the Event Horizon Telescope!

General Relativity in 8 gifs

Until I get this show rolling, I’m going to be posting some of the things I’ve collected over the years that might make for interesting things to do podcasts about down the line!

NGC 3132: The Eight Burst Nebula : Its the dim star, not the bright one, near the center of NGC 3132 that created this odd but beautiful planetary nebula. Nicknamed the Eight-Burst Nebula and the Southern Ring Nebula, the glowing gas originated in the outer layers of a star like our Sun. In this representative color picture, the hot blue pool of light seen surrounding this binary system is energized by the hot surface of the faint star. Although photographed to explore unusual symmetries, its the asymmetries that help make this planetary nebula so intriguing. Neither the unusual shape of the surrounding cooler shell nor the structure and placements of the cool filamentary dust lanes running across NGC 3132 are well understood. via NASA

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Will NASA send astronauts to the moon again or any other planet within the next ten years?

@nasaorion spacecraft will launch on the Space Launch system (the largest spacecraft every built, even bigger than the Saturn V rocket!).  Both are under construction @nasa currently, and this is the spacecraft that will take us beyond the low earth orbit of the International Space Station, whether that be the Moon, Mars, or beyond.  We will conduct test missions with astronauts on Orion in the early 2020s, and a first mission will take us 40,000 miles beyond the Moon!

When the sun sets on Stonehenge on the shortest day of the year, it’s rays align with several important stones.  Twice a year, the streets of Manhattan also line up with the setting sun, a phenomenon dubbed “Manhattanhenge”. Really, most cities with grid systems will see a similar effect (though it’s most dramatic in cities with tall buildings and a view of the true horizon).  You can use a great tool called The Photographer’s Ephemeris to find out the “henge” dates for your city grid - or even individual streets.

Yesterday, (Friday, January 24th) the sun lined up with New York Avenue, a street in DC that runs diagonally up to the White House. (The orange line indicates alignment with the setting sun).

I went out with our multimedia intern Meg Vogel, and captured some images of the sun setting in line with a rather Stonehenge-y sculpture that sits in the middle of that street.

Here are dates for sunset “henge” events in some cities this year:

Manhattan May 25th, July 17th

Philadelphia April 5th, September 6th

Washington DC March 18th, September 24th

Chicago March 16th, September 26th

Phoenix March 20th, September 22nd

Portland, OR March 18th, September 24th

Is your city/town a grid? When’s your henge?

Astronaut tweets