How many light-years can we see outward into the universe?
Table of Contents
How many light-years can we see outward into the universe?
46.1 billion light-years
It’s been 13.8 billion years since the Big Bang, which might lead you to expect that the farthest objects we can possibly see are 13.8 billion light-years away. But not only isn’t that true, the farthest distance we can see is more than three times as remote: 46.1 billion light-years. How can we see so far away?
How far away is 30 billion light-years?
| z8_GND_5296 | |
|---|---|
| Redshift | 7.5078±0.0004 |
| Helio radial velocity | 291622±120 km/s |
| Distance | 13.1 billion ly (4.0 billion pc) (light travel distance) ≈30 billion ly (9.2 billion pc) (present comoving distance) |
| Apparent magnitude (V) | 25.6 (F160W) |
How big is the universe in light years?
Based on what we know so far, the part of the Universe that’s accessible to us today, 13.8 billion years after the Big Bang, is now 46 billion light years in radius. but there’s certainly more, unobservable Universe, perhaps even an infinite amount, just like ours beyond that. There’s likely much more Universe, in all directions, beyond that point.
How far away can we see the universe?
If the Universe is 13.8 billion years old, and the speed of light is truly our cosmic speed limit, how far away should we be able to see? The answer seems obvious: 13.8 billion light-years, since a light-year is the distance light can travel in a year, and nothing can go faster than that.
How many light years can we see?
But 13.8 billion light years is far too small to be the right answer. In actuality, we can see for 46 billion light years in all directions, for a total diameter of 92 billion light years.
Is 92 billion light years big enough?
And so 92 billion light years might seem like a large number for a 13.8 billion year old Universe, but it’s the right number for the Universe we have today, full of matter, radiation, dark energy, and obeying the laws of General Relativity.