astronomerinprogress:

Spacecraft escaping the Solar System

This shows the current positions and other interesting data of the five spacecraft which are leaving the Solar System on escape trajectories - our first emissaries to the stars. On this scale, the nearest star to the Sun would be approximately 100 meters away, and it would take Voyager 1 about 70,000 years to cover that distance.

spaceexp:

The Air Show Presents: “Apollo 11 - As told by Walter Cronkite” [10:12]

spaceplasma:

Animations of Saturn’s aurorae

Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere.  The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the Solar wind pressure: the aurorae become brighter and move closer to the poles when the Solar wind pressure increases.

Credit: ESA/Hubble (M. Kornmesser & L. Calçada)

fouriestseries:

Rotational Stability

Time for an experiment! Find a book and secure it shut using tape or a rubber band. Now experiment with spinning the book while tossing it into the air. You’ll notice that when the book is spun about its longest or shortest axis it rotates stably, but when spun about its intermediate-length axis it quickly wobbles out of control.

Every rigid body has three special, or principal axes about which it can rotate. For a rectangular prism — like the book in our experiment — the principal axes run parallel to the shortest, intermediate-length, and longest edges, each going through the prism’s center of mass. These axes have the highest, intermediate, and lowest moments of inertia, respectively.

When the book is tossed into the air and spun, either about its shortest or longest principal axis, it continues to rotate about that axis forever (or until it hits the floor). For these axes, this indefinite, stable rotation occurs even when the axis of rotation is slightly perturbed.

When spun about its intermediate principal axis, though, the book also continues to rotate about that axis indefinitely, but only if the axis of rotation is exactly in the same direction as the intermediate principal axis. In this case, even the slightest perturbation causes the book to wobble out of control.

The first simulation above shows a rotation about the unstable intermediate axis, where a slight perturbation causes the book to wobble out of control. The second and third simulations show rotations about the two stable axes.

Unfortunately, as far as my understanding goes, there’s no intuitive, non-mathematical explanation as to why rotations about the intermediate principal axis are unstable. If you’re interested, you can find the stability analysis here.

Mathematica code posted here.

Additional sources not linked above: [1[2] [3] [4]

space-pics:

New mass map of a distant galaxy cluster is the most precise yet. The map shows the amount and distribution of mass within MCS J0416.1–2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun.http://space-pics.tumblr.com/

space-pics:

New mass map of a distant galaxy cluster is the most precise yet. The map shows the amount and distribution of mass within MCS J0416.1–2403, a massive galaxy cluster found to be 160 trillion times the mass of the Sun.
http://space-pics.tumblr.com/

s-c-i-guy:

NASA’s Space Launch System: The Future of Space Exploration

Space Launch System, or SLS, begins a bolder mission for NASA and the world — a new era of exploration unlike anything we’re done before. Able to carry more payload than the space shuttle and generate more thrust at launch than the Saturn V, SLS will send the Orion spacecraft farther into space than Apollo ever ventured…and that’s just the first flight!

NASA’s Space Launch System (SLS) will be the most powerful rocket in history for deep-space missions, including to an asteroid and ultimately to Mars. The first flight test of the SLS will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system. As the SLS evolves, it will provide an unprecedented lift capability of 130 metric tons (143 tons) to enable missions even farther into our solar system.

Image credit: NASA

source

sci-universe:

Neil’s words from the last episode of “Cosmos: A Spacetime Odyssey”

allofmymaths:

xysciences:

Representation of mathematically “Completing the square”.

Complicated or not, visual demonstrations are great and the colours are incredibly appealing

allofmymaths:

xysciences:

Representation of mathematically “Completing the square”.

Complicated or not, visual demonstrations are great and the colours are incredibly appealing


The brachistochrone
This animation is about one of the most significant problems in the history of mathematics: the brachistochrone challenge.
If a ball is to roll down a ramp which connects two points, what must be the shape of the ramp’s curve be, such that the descent time is a minimum?
Intuition says that it should be a straight line. That would minimize the distance, but the minimum time happens when the ramp curve is the one shown: a cycloid.
Johann Bernoulli posed the problem to the mathematicians of Europe in 1696, and ultimately, several found the solution. However, a new branch of mathematics, calculus of variations, had to be invented to deal with such problems. Today, calculus of variations is vital in quantum mechanics and other fields.

The brachistochrone

This animation is about one of the most significant problems in the history of mathematics: the brachistochrone challenge.

If a ball is to roll down a ramp which connects two points, what must be the shape of the ramp’s curve be, such that the descent time is a minimum?

Intuition says that it should be a straight line. That would minimize the distance, but the minimum time happens when the ramp curve is the one shown: a cycloid.

Johann Bernoulli posed the problem to the mathematicians of Europe in 1696, and ultimately, several found the solution. However, a new branch of mathematics, calculus of variations, had to be invented to deal with such problems. Today, calculus of variations is vital in quantum mechanics and other fields.

businessgifs:

From the Earth to this GIF. 

businessgifs:

From the Earth to this GIF

tinydot:

Rare photos from the Apollo 11 moon landing (more)

distant-traveller:

What does the Apollo 11 Moon landing site look like today?


Forty-five years ago yesterday, the Sea of Tranquility saw a brief flurry of activity when Neil Armstrong and Buzz Aldrin dared to disturb the ancient lunar dust. Now the site has lain quiet, untouched, for almost half a century. Are any traces of the astronauts still visible?
The answer is yes! Look at the picture above of the site taken in 2012, two years ago. Because erosion is a very gradual process on the moon — it generally takes millions of years for meteors and the sun’s activity to weather features away — the footprints of the Apollo 11 crew have a semi-immortality. That’s also true of the other five crews that made it to the moon’s surface.

Image credit: NASA/GSFC/Arizona State University

distant-traveller:

What does the Apollo 11 Moon landing site look like today?

Forty-five years ago yesterday, the Sea of Tranquility saw a brief flurry of activity when Neil Armstrong and Buzz Aldrin dared to disturb the ancient lunar dust. Now the site has lain quiet, untouched, for almost half a century. Are any traces of the astronauts still visible?

The answer is yes! Look at the picture above of the site taken in 2012, two years ago. Because erosion is a very gradual process on the moon — it generally takes millions of years for meteors and the sun’s activity to weather features away — the footprints of the Apollo 11 crew have a semi-immortality. That’s also true of the other five crews that made it to the moon’s surface.

Image credit: NASA/GSFC/Arizona State University

yknowforkids:

Happy 86th birthday to Vera Rubin (b. July 23, 1928), a pioneering astronomer who uncovered the galaxy rotation problem. While attempting to explain the galaxy rotation problem, she encountered some of the most firm evidence up to that time of dark matter.

Via American Museum of Natural History.

ohstarstuff:

Chandra X-ray Observatory Celebrates 15th Anniversary

To celebrate, the Chandra team released four newly processed images of supernova remnants.

TYCHO
More than four centuries after Danish astronomer Tycho Brahe first observed the supernova that bears his name, the supernova remnant it created is now a bright source of X-rays. The supersonic expansion of the exploded star produced a shock wave moving outward into the surrounding interstellar gas, and another, reverse shock wave moving back into the expanding stellar debris. This Chandra image of Tycho reveals the dynamics of the explosion in exquisite detail. The outer shock has produced a rapidly moving shell of extremely high-energy electrons (blue), and the reverse shock has heated the expanding debris to millions of degrees (red and green). There is evidence from the Chandra data that these shock waves may be responsible for some of the cosmic rays - ultra-energetic particles - that pervade the Galaxy and constantly bombard the Earth.

THE CRAB NEBULA
In 1054 AD, Chinese astronomers and others around the world noticed a new bright object in the sky. This “new star” was, in fact, the supernova explosion that created what is now called the Crab Nebula. At the center of the Crab Nebula is an extremely dense, rapidly rotating neutron star left behind by the explosion. The neutron star, also known as a pulsar, is spewing out a blizzard of high-energy particles, producing the expanding X-ray nebula seen by Chandra. In this new image, lower-energy X-rays from Chandra are red, medium energy X-rays are green, and the highest-energy X-rays are blue.

3C58
3C58 is the remnant of a supernova observed in the year 1181 AD by Chinese and Japanese astronomers. This new Chandra image shows the center of 3C58, which contains a rapidly spinning neutron star surrounded by a thick ring, or torus, of X-ray emission. The pulsar also has produced jets of X-rays blasting away from it to both the left and right, and extending trillions of miles. These jets are responsible for creating the elaborate web of loops and swirls revealed in the X-ray data. These features, similar to those found in the Crab, are evidence that 3C58 and others like it are capable of generating both swarms of high-energy particles and powerful magnetic fields. In this image, low, medium, and high-energy X-rays detected by Chandra are red, green, and blue respectively.

G292.0+1.8:
At a distance of about 20,000 light years, G292.0+1.8 is one of only three supernova remnants in the Milky Way known to contain large amounts of oxygen. These oxygen-rich supernovas are of great interest to astronomers because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people. The X-ray image from Chandra shows a rapidly expanding, intricately structured, debris field that contains, along with oxygen (yellow and orange), other elements such as magnesium (green) and silicon and sulfur (blue) that were forged in the star before it exploded.

Credit: 
http://chandra.harvard.edu