The youngest and most distant galaxy cluster (image: NASA/CXC/INAF/S.Andreon et al, DSS; ESO/VLT)
Speed of light is very important in astronomy. Due to the vast distances involved, it can take a very long time for light to travel from its source to Earth. The fact that farther-away objects appear younger (due to the finite speed of light) allows astronomers to infer the evolution of stars, of galaxies, and of the universe itself.
Astronomical distances are often expressed in light-years. A light‑year is the distance light travels in one year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs.
Reflected sunlight from the Moon’s surface takes 1.2–1.3 seconds to travel the distance to the Earth’s surface. It takes approximately 499 seconds (8.32 minutes) for light to travel from the Sun. The most distant space probe, Voyager 1, is about 15 light-hours away from Earth. The nearest known star Proxima Centauri is about 4.22 light-years away. The Milky Way is about 100,000 light-years across. The Andromeda Galaxy is approximately 2.5 million light-years away.
JKCS 041 is a group of galaxies in the constellation Cetus with the distinction of being the farthest away group from Earth ever observed. It is estimated to be 10.2 billion light years away. Watching this distant object astronomers found out how the universe used to be at only one quarter of the present age (3.5 billion years after the big bang). And they don’t expect to find many more galaxy clusters at distances father than JKCS 041. They don’t think gravity can work fast enough to make galaxy clusters much earlier. The universe tends to assemble smaller objects first. These structures then combine into larger ones.
The most distant object yet confirmed in the universe – a ten-second-long spectacular burst of gamma rays in the constellation Leo. A self destructing star exploded 13.1 billion light years from Earth exploded on April 23, 2009. It detonated just 630 million years after the big bang, around the end of the cosmic “dark ages”, when the first stars and galaxies were lighting up space.
Loading ...