Black holes do not emit light, so we cannot observe them directly
The mass of a black hole can be measured by observing the orbits of objects around it, such as stars or gas clouds. By studying the gravitational effects of the black hole on these objects, astronomers can calculate its mass. Another method is to measure the distortion of light from objects behind the black hole, known as gravitational lensing, which can provide information about the black hole's mass.
Astronomers know because they have studied star patterns and placements and know when there has been a change between where there is a black hole and where there isn't one.
By observing the movement of nearby objects.
Astronomers indicate the probability of us all really going to be sucked into a black hole to be quite low.
X-rays are the best band for studying black holes as the radiations emitted by the black hole is X-rays so we can expect the presence of a black hole anywhere in the Universe.
A black hole or a worm hole :) good luck
A black hole, exoplanets. It has always been inferred.
You cant see a black hole because the gravitational pull of it is so strong that not even light can escape from it. Astronomers find them through observing the space matter that they pull into them, not the hole itself.
Astronomers believe that black holes exist in the center of every universe. They even think that there may be a black hole in the center of our galaxy, the Milky Way
Astronomers say that there are several, possibly many, black holes, all a long way from Earth.
Astronomers look for black holes by searching for their effects (the hole itself by definition can't be seen). Some of the possible effects are gravitational lensing and electromagnetic radiation from the hole's accretion disk.
By observing the movement of nearby objects. The gravity of the black hole will accelerate such an object according to Newton's Second Law (F=ma). More specifically, the details of the orbit of a star that moves around the black hole will vary, depending on the black hole's mass.