Black holes can have a mass anywhere from a few solar masses (for stellar black holes), to about 20 billion solar masses (for the largest known supermassive black holes, in the centers of galaxies). The radius of a black hole (more precisely, of its event horizon) is directly proportional to its mass; a black hole with the mass of the Sun would have a radius of about 3 km, one that has a million times the mass of the Sun would have a radius a million times as much, etc.
Nope.. Light always travels at the same speed. However, black holes do affect the trajectory of the photons, hense diverting the direction of the light.
The Milky Way galaxy takes about 200-250 million years to complete one full rotation. This rotation speed varies based on the distance from the center of the galaxy, with stars closer to the center orbiting faster than those further out.
Astronomers can determine the rotation of a galaxy by measuring the Doppler shift of the light emitted by stars and gas within the galaxy. The rotation speed can be calculated by observing the difference in wavelengths of light from objects moving towards or away from us. This information allows scientists to create maps of how the galaxy's stars and gas are moving.
There are hypotheses about so called 'virtual particles' that may travel faster than speed of light, and hence are not sucked up by Black Holes. Also, Black Holes cannot suck another bigger Black Hole, when they meet a bigger one, they get sucked up rather.
By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.By observing the rotation, and calculating the diameter. If you know the diameter of the galaxy, a certain rotation speed implies a certain mass (to be stable at that speed). It turns out there is 5-10 times more mass than the known masses. Read about "dark mass" for more details.
as high as 98.7% of the speed of light
No, black holes do not move at the speed of light. While they can exert a strong gravitational pull, their movement is not necessarily tied to the speed of light.
The Andromeda galaxy rotates at a speed of about 100 to 200 kilometers per second at its outer edges, and faster towards its center. It takes approximately 200 million years for Andromeda to complete one full rotation.
The speed of rotation of a galaxy is related to the mass of the galaxy. Most galaxies appear to be spinning more quickly than their masses could account for, leading some scientists to believe that (many? most?) galaxies are heavier than they appear to be. So if there is a lot of extra mass that we cannot see, a black hole is a logical supposition. We can't prove it - yet - but many astronomers believe that supermassive black holes may reside in the centers of most galaxies.
Nope.. Light always travels at the same speed. However, black holes do affect the trajectory of the photons, hense diverting the direction of the light.
Obstructions, black holes, etc.
The Milky Way galaxy takes about 200-250 million years to complete one full rotation. This rotation speed varies based on the distance from the center of the galaxy, with stars closer to the center orbiting faster than those further out.
A black hole has an escape velocity of the speed of light, at least theoretically. Oddly, though, each galaxy has a black hole and we can detect them because they throw off massive amounts of energy. If the escape velocity is greater than the speed of light, then no light or energy of any kind should escape. So black holes are not quite the perfect consumers of everything.
Everything is moving away from everything else at the same speed, so black holes moving is relative to where you are.
Astronomers can determine the rotation of a galaxy by measuring the Doppler shift of the light emitted by stars and gas within the galaxy. The rotation speed can be calculated by observing the difference in wavelengths of light from objects moving towards or away from us. This information allows scientists to create maps of how the galaxy's stars and gas are moving.
No. The escape velocity of a black hole is greater than the speed of light.
Scientists believe that a great may of the galaxies of all types may have black holes in their centers. One of the reasons is that most things in space, including most galaxies, rotate. (If they were standing still, their mutual gravitational attraction would drag them into each other.) We can sometimes measure the speed of the rotation, and calculate how much mass the galaxy must have in order to hold itself together - because rotation tends to pull things apart. For most galaxies, we can't see enough mass to hold them together. Gravity is the "glue" that keeps spinning things together, and gravity comes from mass. So the only thing that holds those spinning galaxies together would be "invisible" mass. Some scientists have theorized about "dark matter", adding mass but being invisible. Black holes also add mass, and aren't visible, and are the simpler explanation.