Andromeda (M31) E Triangolo (M33), Le Due Galassie Giganti Più Vicine Alla Nostra Via Lattea. Queste,

Ship Ready for Return (Unfinished) - Chesley Bonestell

Come fare pisolini nello spazio 😴

I think we made something entirely new

New Horizons ha ufficialmente finito la sua missione primaria! L'ultimo bit di dati ottenuti durante il fly-by del 14 luglio 2015 è stato ricevuto dalla stazione di terra della NASA, a Canberra in Australia, martedì alle 11.48 ora italiana.

Questa sonda ha collezionato più di 50 GB di dati durante il suo paesaggio ravvicinato intorno a Plutone e Caronte e li ha inviati a terra impiegando poco più di un intero anno. La velocità di downlink è stata di 2'000 bit al secondo, una minuscola frazione rispetto alle connessioni a cui siamo abituati. Ora può iniziare la lunga fase di processing dei dati completi, che per adesso sono solo lunghe catene di 0 e 1.

Gli ingegneri di missione effettueranno un'ultima data review prima di cancellare definitivamente i dati sui due hard disk presenti a bordo della sonda, in vista delle nuove osservazioni scientifiche previste per il 2019. Il primo gennaio di quell'anno, infatti, New Horizons passerà a soli 3'000 km da 2014MU69, un antico corpo celeste presente ai confini del nostro sistema solare e scoperto due anni fa dal telescopio Hubble.

Nell'immagine potete vedere una delle scoperte più fresche del team di New Horizons: possibili nuvole intorno ai rilievi montuosi di Plutone.

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

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TODAY IN HISTORY: On October 18, 1989, the Galileo space probe launched from Cape Canaveral, Florida aboard the Space Shuttle Atlantis, heading out on a decade-plus mission to explore Jupiter and its neighbors. This early ‘80s NASA simulation footage shows how the spacecraft would eventually release a probe for a one-way trip into the turbulent Jovian atmosphere.

40 YEARS AGO TODAY: The surface of Mars, as seen by NASA’s Viking 2 lander, September 25, 1977.

Visions of the Future

by NASA/JPL (Jet Propulsion Laboratory)