Constellation Cetus

ON THIS DAY: Titan, moon of Saturn, observed on November 30, 2014 by the Cassini space probe.

(NASA)

Andromeda (M31) e Triangolo (M33), le due galassie giganti più vicine alla nostra Via Lattea. Queste, insieme ad una trentina di più "piccole" fanno parte del Gruppo Locale (si stima che il suo diametro sia di 4 milioni di anni luce!)

Modifiche in multistrato, indicazioni segnate a penna e si va ad allunare

Solar System

via reddit

Enceladus striated surface as seen by Cassini .

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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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James Hall Nasmyth - Full Moon - 1874 - via Eastman Museum

On March 2, 1963 Engineer Thomas Byrdsong checks the Apollo/Saturn 1B Ground-wind-loads model in the Transonic Dynamics Tunnel at Langley Research Center in Hampton, Virginia. Credit: NASA

Spaceships ❤

The Past, Present and Future of Exploration on Mars

Today, we’re celebrating the Red Planet! Since our first close-up picture of Mars in 1965, spacecraft voyages to the Red Planet have revealed a world strangely familiar, yet different enough to challenge our perceptions of what makes a planet work.

You’d think Mars would be easier to understand. Like Earth, Mars has polar ice caps and clouds in its atmosphere, seasonal weather patterns, volcanoes, canyons and other recognizable features. However, conditions on Mars vary wildly from what we know on our own planet.

Join us as we highlight some of the exploration on Mars from the past, present and future:

PAST

Viking Landers

Our Viking Project found a place in history when it became the first U.S. mission to land a spacecraft safely on the surface of Mars and return images of the surface. Two identical spacecraft, each consisting of a lander and an orbiter, were built. Each orbiter-lander pair flew together and entered Mars orbit; the landers then separated and descended to the planet’s surface.

Besides taking photographs and collecting other science data, the two landers conducted three biology experiments designed to look for possible signs of life.

Pathfinder Rover

In 1997, Pathfinder was the first-ever robotic rover to land on the surface of Mars. It was designed as a technology demonstration of a new way to deliver an instrumented lander to the surface of a planet. Mars Pathfinder used an innovative method of directly entering the Martian atmosphere, assisted by a parachute to slow its descent and a giant system of airbags to cushion the impact.

Pathfinder not only accomplished its goal but also returned an unprecedented amount of data and outlived its primary design life.

PRESENT

Spirit and Opportunity

In January 2004, two robotic geologists named Spirit and Opportunity landed on opposite sides of the Red Planet. With far greater mobility than the 1997 Mars Pathfinder rover, these robotic explorers have trekked for miles across the Martian surface, conducting field geology and making atmospheric observations. Carrying identical, sophisticated sets of science instruments, both rovers have found evidence of ancient Martian environments where intermittently wet and habitable conditions existed.

Both missions exceeded their planned 90-day mission lifetimes by many years. Spirit lasted 20 times longer than its original design until its final communication to Earth on March 22, 2010. Opportunity continues to operate more than a decade after launch.

Mars Reconnaissance Orbiter

Our Mars Reconnaissance Orbiter left Earth in 2005 on a search for evidence that water persisted on the surface of Mars for a long period of time. While other Mars missions have shown that water flowed across the surface in Mars’ history, it remained a mystery whether water was ever around long enough to provide a habitat for life.

In addition to using the rover to study Mars, we’re using data and imagery from this mission to survey possible future human landing sites on the Red Planet.

Curiosity

The Curiosity rover is the largest and most capable rover ever sent to Mars. It launched November 26, 2011 and landed on Mars on Aug. 5, 2012. Curiosity set out to answer the question: Did Mars ever have the right environmental conditions to support small life forms called microbes? 

Early in its mission, Curiosity’s scientific tools found chemical and mineral evidence of past habitable environments on Mars. It continues to explore the rock record from a time when Mars could have been home to microbial life.

FUTURE

Space Launch System Rocket

We’re currently building the world’s most powerful rocket, the Space Launch System (SLS). When completed, this rocket will enable astronauts to begin their journey to explore destinations far into the solar system, including Mars.

Orion Spacecraft

The Orion spacecraft will sit atop the Space Launch System rocket as it launches humans deeper into space than ever before. Orion will serve as the exploration vehicle that will carry the crew to space, provide emergency abort capability, sustain the crew during the space travel and provide safe re-entry from deep space return velocities.

Mars 2020

The Mars 2020 rover mission takes the next step in exploration of the Red Planet by not only seeking signs of habitable conditions in the ancient past, but also searching for signs of past microbial life itself.

The Mars 2020 rover introduces a drill that can collect core samples of the most promising rocks and soils and set them aside in a “cache” on the surface of Mars. The mission will also test a method for producing oxygen from the Martian atmosphere, identify other resources (such as subsurface water), improve landing techniques and characterize weather, dust and other potential environmental conditions that could affect future astronauts living and working on the Red Planet.

For decades, we’ve sent orbiters, landers and rovers, dramatically increasing our knowledge about the Red Planet and paving the way for future human explorers. Mars is the next tangible frontier for human exploration, and it’s an achievable goal. There are challenges to pioneering Mars, but we know they are solvable. 

To discover more about Mars exploration, visit: https://www.nasa.gov/topics/journeytomars/index.html

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