NASA-funded Website Lets Public Search For New Nearby Worlds

Black holes

A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways a black hole acts like an ideal black body, as it reflects no light.  

The idea of a body so massive that even light could not escape was briefly proposed by astronomical pioneer and English clergyman John Michell in a letter published in November 1784. Michell’s simplistic calculations assumed that such a body might have the same density as the Sun, and concluded that such a body would form when a star’s diameter exceeds the Sun’s by a factor of 500, and the surface escape velocity exceeds the usual speed of light.

At the center of a black hole, as described by general relativity, lies a gravitational singularity, a region where the spacetime curvature becomes infinite. For a non-rotating black hole, this region takes the shape of a single point and for a rotating black hole, it is smeared out to form a ring singularity that lies in the plane of rotation. In both cases, the singular region has zero volume. It can also be shown that the singular region contains all the mass of the black hole solution. The singular region can thus be thought of as having infinite density. 

How Do Black Holes Form?

Scientists think the smallest black holes formed when the universe began.

Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.

Scientists think supermassive black holes were made at the same time as the galaxy they are in.

Supermassive black holes, which can have a mass equivalent to billions of suns, likely exist in the centers of most galaxies, including our own galaxy, the Milky Way. We don’t know exactly how supermassive black holes form, but it’s likely that they’re a byproduct of galaxy formation. Because of their location in the centers of galaxies, close to many tightly packed stars and gas clouds, supermassive black holes continue to grow on a steady diet of matter.

If Black Holes Are “Black,” How Do Scientists Know They Are There?

A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. 

Scientists can study stars to find out if they are flying around, or orbiting, a black hole.

When a black hole and a star are close together, high-energy light is made. This kind of light can not be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.

On 11 February 2016, the LIGO collaboration announced the first observation of gravitational waves; because these waves were generated from a black hole merger it was the first ever direct detection of a binary black hole merger. On 15 June 2016, a second detection of a gravitational wave event from colliding black holes was announced. 

Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background 

Animated simulation of gravitational lensing caused by a black hole going past a background galaxy. A secondary image of the galaxy can be seen within the black hole Einstein ring on the opposite direction of that of the galaxy. The secondary image grows (remaining within the Einstein ring) as the primary image approaches the black hole. The surface brightness of the two images remains constant, but their angular size varies, hence producing an amplification of the galaxy luminosity as seen from a distant observer. The maximum amplification occurs when the background galaxy (or in the present case a bright part of it) is exactly behind the black hole.

Could a Black Hole Destroy Earth?

Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.

Even if a black hole the same mass as the sun were to take the place of the sun, Earth still would not fall in. The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now.

The sun will never turn into a black hole. The sun is not a big enough star to make a black hole.

More posts about black holes

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Coronal mass ejection

A coronal mass ejection (CME) is a significant release of plasma and magnetic field from the solar corona. They often follow solar flares and are normally present during a solar prominence eruption. The plasma is released into the solar wind, and can be observed in coronagraph imagery.

Coronal mass ejections are often associated with other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established. CMEs most often originate from active regions on the Sun’s surface, such as groupings of sunspots associated with frequent flares. Near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days.

Coronal mass ejections release large quantities of matter and electromagnetic radiation into space above the Sun’s surface, either near the corona (sometimes called a solar prominence), or farther into the planetary system, or beyond (interplanetary CME). The ejected material is a magnetized plasma consisting primarily of electrons and protons. While solar flares are very fast (being electromagnetic radiation), CMEs are relatively slow.

Coronal mass ejections are associated with enormous changes and disturbances in the coronal magnetic field. They are usually observed with a white-light coronagraph.

Impact on Earth

When the ejection is directed towards Earth and reaches it as an interplanetary CME (ICME), the shock wave of traveling mass causes a geomagnetic storm that may disrupt Earth’s magnetosphere, compressing it on the day side and extending the night-side magnetic tail. When the magnetosphere reconnects on the nightside, it releases power on the order of terawatt scale, which is directed back toward Earth’s upper atmosphere.

Solar energetic particles can cause particularly strong aurorae in large regions around Earth’s magnetic poles. These are also known as the Northern Lights (aurora borealis) in the northern hemisphere, and the Southern Lights (aurora australis) in the southern hemisphere.

Coronal mass ejections, along with solar flares of other origin, can disrupt radio transmissions and cause damage to satellites and electrical transmission line facilities, resulting in potentially massive and long-lasting power outages.

To learn more, click here.

Image credit: Alex Conu 

Animation: Science Channel & NASA/Goddard

Southern Craters and Galaxies : The Henbury craters in the Northern Territory, Australia, planet Earth, are the scars of an impact over 4,000 years old. When an ancient meteorite fragmented into dozens of pieces, the largest made the 180 meter diameter crater whose weathered walls and floor are lit in the foreground of this southern hemisphere nightscape. The vertical panoramic view follows our magnificent Milky Way galaxy stretching above horizon, its rich central starfields cut by obscuring dust clouds. A glance along the galactic plane also reveals Alpha and Beta Centauri and the stars of the Southern Cross. Captured in the regions spectacular, dark skies, the Small Magellanic Cloud, satellite of the Milky Way, is the bright galaxy to the left. Not the lights of a nearby town, the visible glow on the horizon below it is the Large Magellanic Cloud rising. via NASA

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Saturn and Mars visit Milky Way Star Clouds : Planets, stars, nebulas and a galaxy this impressive image has them all. Closest to home are the two planets Mars , visible as the two bright orange spots in the upper half of the featured image. On the central right are the colorful Rho Ophiuchus star clouds featuring the bright orange star Antares lined up below Mars. These interstellar clouds contain both red emission nebulas and blue reflection nebulas. At the top right of the image is the Blue Horsehead reflection nebula. On the lower left are many dark absorption nebulas that extend from the central band of our Milky Way Galaxy. The featured deep composite was composed of multiple deep exposures taken last month from Brazil. Although you need a telescope to see the nebulosities, Saturn and Mars will remain visible to the unaided eye this month toward the east, just after sunset. via NASA

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Earth and Space Station

View of a single engine orbital maneuvering system (OMS) firing on the Discovery. The payload bay is open and the protective canisters for the AUSSAT communications satellite (open) and the ASC-1 are visible. A cloudy Earth’s horizon can be seen above the orbiter … #Astronomy #Space #Spacegram #Spaceflight #Nasa #ESA #ASI #Astronaut #Universe #Cosmos #Sky #Earth #Nebula #Galaxy #Love #MarsGeneration #TheMarsGeneration #MoonColonist #Moon #Astro_Lorenzo

Elephant Trunk Nebula

When radiation and winds from massive young stars impact clouds of cool gas, they can trigger new generations of stars to form. This is what may be happening in this object known as the Elephant Trunk Nebula (or its official name of IC 1396A).  

Image credit: X-ray: NASA/CXC/PSU/Getman et al, Optical: DSS, Infrared: NASA/JPL-Caltech

The Butterfly Nebula from Hubble

via reddit

for all the space ppl out there, nasa is doing a live feed of earth in space on youtube rn! 👀💫🌍