Astronomy And Astrophysics: Facts

Composed of gas and dust, the pictured pillar resides in a tempestuous stellar nursery called the Carina Nebula, located 7500 light-years away in the southern constellation of Carina.

Credit: NASA, ESA and the Hubble SM4 ERO Team

Eight curiosities about black holes

In this post contains some facts and curiosities about one of the most extreme objects in the universe - Black Holes. Black holes are some of the strangest and most fascinating objects found in outer space. They are objects of extreme density, with such strong gravitational attraction that even light cannot escape from their grasp if it comes near enough.

1° A Massive Star Collapsing In Upon Itself

Say you have a star that’s about 20 times more massive than the Sun. Our Sun is going to end its life quietly; when its nuclear fuel burns out, it’ll slowly fade into a white dwarf. That’s not the case for far more massive stars. When those monsters run out of fuel, gravity will overwhelm the natural pressure the star maintains to keep its shape stable. When the pressure from nuclear reactions collapses, according to the Space Telescope Science Institute, gravity violently overwhelms and collapses the core and other layers are flung into space. This is called a supernova. The remaining core collapses into a singularity — a spot of infinite density and almost no volume. That’s another name for a black hole.

2° Black holes come in a range of sizes.

There are at least three types of black holes, ranging from relative squeakers to those that dominate a galaxy’s center. Primordial black holes are the smallest kinds, and range in size from one atom’s size to a mountain’s mass. Stellar black holes, the most common type, are up to 20 times more massive than our own Sun and are likely sprinkled in the dozens within the Milky Way. And then there are the gargantuan ones in the centers of galaxies, called “supermassive black holes.” They’re each more than one million times more massive than the Sun. How these beasts formed is still being examined.

3° The first black hole wasn’t discovered until X-ray astronomy was used

Cygnus X-1 was first found during balloon flights in the 1960s, but wasn’t identified as a black hole for about another decade. According to NASA, the black hole is 10 times more massive to the Sun. Nearby is a blue supergiant star that is about 20 times more massive than the Sun, which is bleeding due to the black hole and creating X-ray emissions.

4° Black holes are only dangerous if you get too close

Like creatures behind a cage, it’s okay to observe a black hole if you stay away from its event horizon — think of it like the gravitational field of a planet. This zone is the point of no return, when you’re too close for any hope of rescue. But you can safely observe the black hole from outside of this arena. By extension, this means it’s likely impossible for a black hole to swallow up everything in the Universe (barring some sort of major revision to physics or understanding of our Cosmos, of course.)

5° We aren’t sure if wormholes exist

A popular science-fiction topic concerns what happens if somebody falls into a black hole. Some people believe these objects are a sort of wormhole to other parts of the Universe, making faster-than-light travel possible. But as this Smithsonian Magazine article points out, anything is possible since we still have a lot to figure out about physics. “Since we do not yet have a theory that reliably unifies general relativity with quantum mechanics, we do not know of the entire zoo of possible spacetime structures that could accommodate wormholes,” said Abi Loeb, who is with the Harvard-Smithsonian Center for Astrophysics.

6°  Black holes will spaghettify you and everything else

If a person was able to survive long enough to describe falling into a black hole, he would at first experience weightless as he goes into free fall, but then feel intense “tidal” gravitational forces as he got closer to the center of the black hole. In other words, if his feet were closer to the centre than his head, then they would feel a stronger pull until he eventually is stretched and then ripped apart. As he falls in he may observe distorted images as the light bends around him and he will also still be able to see beyond the black hole as light continues to reach him from the outside.

7° Weird time stuff happens around black holes

This is best illustrated by one person (call them Unlucky) falling into a black hole while another person (call them Lucky) watches. From Lucky’s perspective, Unlucky’s time clock appears to be ticking slower and slower. This is in accordance with Einstein’s theory of general relativity, which (simply put) says that time is affected by how fast you go, when you’re at extreme speeds close to light. The black hole warps time and space so much that Unlucky’s time appears to be running slower. From Unlucky’s perspective, however, their clock is running normally and Lucky’s is running fast.

8° Massive Black Hole in The Center Of Milky Way 

It is now thought that most galaxies are held together by supermassive black holes at their centers, which cluster hundreds of solar systems around them. In fact, 30,000 light years away at the centre of our own Milky Way galaxy is a black hole with 30 million times the mass of our own sun.

Source: space.com, universetoday.com, sciencealert.com & astronomytrek.com

A boulder-strewn field of red rocks stretches across the horizon in this self-portrait of Viking 2 on Mars’ Utopian Plain. Viking 2 landed Sept. 3,1976, some 4,600 miles from the twin Viking 1 craft, which touched down on July 20.  

Image Credit: NASA/JPL

Spacewalk Recap Told in GIFs

Friday, Oct. 20, NASA astronauts Randy Bresnik and Joe Acaba ventured outside the International Space Station for a 6 hour and 49 minute spacewalk. Just like you make improvements to your home on Earth, astronauts living in space periodically go outside the space station to make updates on their orbiting home.

During this spacewalk, they did a lot! Here’s a recap of their day told in GIFs…

All spacewalks begin inside the space station. Astronauts Paolo Nespoli and Mark Vande Hei helped each spacewalker put on their suit, known as an Extravehicular Mobility Unit (EMU).

They then enter an airlock and regulate the pressure so that they can enter the vacuum of space safely. If they did not regulate the pressure safely, the astronauts could experience something referred to as “the bends” – similar to scuba divers.

Once the two astronauts exited the airlock and were outside the space station, they went to their respective work stations.

Bresnik replaced a failed fuse on the end of the Dextre robotic arm extension, which helps capture visiting vehicles.

During that time, Acaba set up a portable foot restraint to help him get in the right position to install a new camera.

While he was getting set up, he realized that there was unexpected wearing on one of his safety tethers. Astronauts have multiple safety mechanisms for spacewalking, including a “jet pack” on their spacesuit. That way, in the unlikely instance they become untethered from the station, the are able to propel back to safety.

Bresnik was a great teammate and brought Acaba a spare safety tether to use.

Once Acaba secured himself in the foot restraint that was attached to the end of the station’s robotic arm, he was maneuvered into place to install a new HD camera. Who was moving the arm? Astronauts inside the station were carefully moving it into place!

And, ta da! Below you can see one of the first views from the new enhanced HD camera…(sorry, not a GIF).

After Acaba installed the new HD camera, he repaired the camera system on the end of the robotic arm’s hand. This ensures that the hand can see the vehicles that it’s capturing.

Bresnik, completed all of his planned tasks and moved on to a few “get ahead” tasks. He first started removing extra thermal insulation straps around some spare pumps. This will allow easier access to these spare parts if and when they’re needed in the future.

He then worked to install a new handle on the outside of space station. That’s a space drill in the above GIF. 

After Acaba finished working on the robotic arm’s camera, he began greasing bearings on the new latching end effector (the arm’s “hand”), which was just installed on Oct. 5.

The duo completed all planned spacewalk tasks, cleaned up their work stations and headed back to the station’s airlock. 

Once safely inside the airlock and pressure was restored to the proper levels, the duo was greeted by the crew onboard. 

They took images of their spacesuits to document any possible tears, rips or stains, and took them off. 

Coverage ended at 2:36 p.m. EDT after 6 hours and 49 minutes. We hope the pair was able to grab some dinner and take a break!

You can watch the entire spacewalk HERE, or follow @Space_Station on Twitter and Instagram for regular updates on the orbiting laboratory. 

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

To Scale Solar System Replica in the Desert!

Drilling Through Ice in the Hunt of Celestial Life

The Extraordinary Core of a Neutron Star

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

Low genetic diversity is a problem when you’re founding a new colony, so how would we avoid that on another planet?

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