The Hubble Telescope has just located a star that’s 12.9 billion light-years away. Find out why this discovery offers new insights into how our Universe began.
When I began stargazing with a telescope decades ago, one of the things that struck me was that looking out into space also means looking back in time. Because the speed of light is fixed, there’s a travel time between the origin of an object’s light and when that light arrives here on Earth.
That lag time is only about a second when we look at the moon. Even for a distant planet like Saturn, it only amounts to roughly an hour-and-a-half.
Even so, it can get mind-blowing when we look outside our Solar System. For example, the light from a nebula in the constellation Orion is 1,350 years old once it hits my eyeball. The light from the Andromeda Galaxy, the Milky Way’s nearest neighbour, is more than 2.5 million years old.
Furthest, and Therefore Oldest Star We’ve Ever Seen
This week, the science journal Nature reported that the Hubble Telescope has left all those distances in the dust. It broke its own record by finding the furthest, and therefore the oldest, star we’ve ever seen.
Astronomer Brian Welch of Johns Hopkins University, the lead author of the study, named this faraway star Earendel. That’s the Old English word for “morning star.”
The light from this newfound star is 12.9 billion years old. That tells us it was out there when the Universe was only about 7% of its age today.
Gravitational Lensing from Galaxy Cluster
Normally, even the Hubble Telescope can’t show us clear images of individual stars that far away. The researchers managed to find this one because of an effect called gravitational lensing.
Gravity results from massive objects in space warping the fabric of space time. The warping effect can create a kind of natural lens that magnifies anything behind it.
In this case, there is a galaxy cluster called WHL0137-08 in between Earth and Earendel. Its gravitational lens distorts and amplifies the light coming from this ancient star.
“Magnified and Distorted into Sunrise Arc”
Professor Welch explains, “The galaxy hosting this star has been magnified and distorted by gravitational lensing into a long crescent that we named the Sunrise Arc.”
Opticians call the lensing effect from this ripple in space a “caustic.” It’s like when you see bright light patterns on the bottom of a pool from ripples on the surface.
The lensing makes Earendel at least a thousand times brighter than normal. That makes it clearly visible using the Hubble Telescope, even though it’s inside a galaxy of its own.
One of the Most Massive Stars in the Universe
Earendel is about 50 times the mass of our Sun and many millions of times brighter. It seems to be one of the most massive stars in the Universe.
Typically, stars this size have a companion star as part of a binary system. At this stage, astronomers can’t tell if Earendel is also a binary star.
Scientists belive that this lensing effect will be going on for quite a few years. That should give the Hubble Telescope’s replacement, the James Webb Space Telescope a chance to observe it as well.
Hope to Confirm Surise Arc Contains No Heavy Elements
A key thing astronomers hope to confirm is that the Sunrise Arc contains no heavy elements. This would confirm the idea that only hydrogen and helium existed in the early Universe, and that heavier elements formed later as the Universe expanded.
This ability to look back in time by looking out into space has been a tremendous boon to cosmologists trying to unearth the New Story of how our Universe was born. If it weren’t for this effect, we’d be literally in the dark about events that took place many eons ago.
Origin of the Universe and of Humanity
The better science gets at taking advantage of light’s travel time from distant objects, the more we can learn about the Universe’s origins. The Universe isn’t away off in “outer space.” We’re all a part of it, which means that we’re also learning about Humanity’s origins at the same time.
Professor Welch wound things up on this point, saying, “With Webb, we may see stars even farther than Earendel, which would be incredibly exciting. We’ll go as far back as we can. I would love to see Webb break Earendel’s distance record.”
We always have more to learn if you dare to know.
Record Broken: Hubble Spots Farthest Star Ever Seen
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