astronomy test 2

if our sun were to become a black hole, the radius of its event horizon would be about

3 kilometers

the objects created by the merger of two black holes is

a single black hole with mass slightly lower than the sum of the merging ones

When laser beams in an interferometer combine

an interference pattern of bright and dark light is formed

after traveling 140 million light years from the 170817 neutron star merger, gravitational waves and gamma rays

arrived at earth at almost exactly the same time

the gravitational wave signal from merging black holes is called a "chirp" because

as the black holes get closer, the signal frequency and amplitude increase

according to general relativity, the presence of mass

causes a curvature (or warping) of spacetime

current measurements of the hubble constant Ho

disagree depending on the method used

The region around a black hole where everything is trapped, and nothing can get out to interact with the rest of the universe, is called

event horizon

after a star collapses to form a black hole, the only information we can measure is

it's mass and spin

a gravitational lens is formed by

mass between the source and earth

space time effects like time dilation are only noticeable when

objects move close to the speed of light

When astronauts aboard the International Space Station (ISS) in space let go of an orange, it just floats there. Why is that?

the ISS is falling around the Earth, and in free fall, things feel no weight

A student shines a flashlight out the window of a very fast rocket. If the normal speed of light is c, then

the light always travels at speed c

in the first detection of gravitational waves by LIGO in 2015, the waves came from

the merger of two black holes

the first time that astronomers observed both gravitational waves and electromagnetic waves from the same event, what they were observing was:

the merger of two neutron stars

observations of the spectra of the afterglow of the binary neutron star merger revealed

the presence of newly created heavy elements

the speed of gravitational waves travel is

the speed of light

The main postulate of special relativity is that

the speed of light is an absolute constant

according to general relativity, in a freely falling reference frame, light follows

travels in a straight line

in the 2015 gravitational wave discovery event, the two black holes

were each about 30 solar masses