Eclipses make the sun's gravitational light bending visible
During night-like conditions created during the totality of a solar eclipse, like that of April 8, planets and stars are visible. Venus and Jupiter, bracketing the sun, will be very noticeable, while Mercury will be rather ...
There won't be any bright stars near the sun during this eclipse, but, amazingly, dim stars near it will appear displaced by a small amount due to its gravity. This displacement, and the motion of Mercury, were the earliest evidence in the early 20th century that confirmed Einstein's new theory of gravity. These observations also led directly to the prediction of black holes.
With the amazing power of modern telescopes, our "best of" astronomy websites have abundant evidence of gravity bending light, acting like a lens. If the alignment of a background object with a gravity lens is almost perfect, an "Einstein ring" of light appears like a halo around it.
With the amazing power of modern telescopes, our "best of" astronomy websites have abundant evidence of gravity bending light, acting like a lens. If the alignment of a background object with a gravity lens is almost perfect, an "Einstein ring" of light appears like a halo around it.
Bending light
The earliest modern studies of light were published by Sir Isaac Newton in the early 18th century. Despite some of his discoveries now being strong evidence for light being waves, he concluded at the time that light was made of particles and would indeed be affected by gravity.
The French mathematician Pierre-Simon Laplace even proposed, in 1795, that gravity could be strong enough to pull light into a body, an early concept of black holes. However, by the late 19th century, Newton's ideas on light were discarded, and it was thought to be waves, and thus unaffected by gravity.
The earliest modern studies of light were published by Sir Isaac Newton in the early 18th century. Despite some of his discoveries now being strong evidence for light being waves, he concluded at the time that light was made of particles and would indeed be affected by gravity.
The French mathematician Pierre-Simon Laplace even proposed, in 1795, that gravity could be strong enough to pull light into a body, an early concept of black holes. However, by the late 19th century, Newton's ideas on light were discarded, and it was thought to be waves, and thus unaffected by gravity.
An image of GAL-CLUS-022058s — the largest and one of the most complete Einstein rings ever discovered. Credit: ESA/Hubble & NASA, S. Jha
A graph showing the bending of starlight by the sun as observed in Australia during an eclipse in 1922. The arrows are at a scale about 2,500 times larger than the circle that represents the sun; the tiny effect makes them look farther from the sun than they actually are. Credit: W. W. Campbell and R. J. Trumpler/Lick Observatory Bulletin
Sagittarius A*, the black hole at the center of the Milky Way galaxy, is about 5 million times as massive as the sun. Credit: EHT Collaboration