Philippa Kaur
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The James Webb telescope found ‘Green Pea’ galaxies in the early universe
Galaxies that helped transform the early universe may have been small, round and green.
Astronomers using the James Webb Space Telescope have spotted “Green Pea” galaxies dating to 13.1 billion years ago. These viridescent runts, spotted just 700 million years after the Big Bang, might have helped trigger one of the greatest makeovers in cosmic history, astronomers said at a January 9 news conference in Seattle at the American Astronomical Society’s annual meeting.
Green Peas first showed up in 2009 in images from the Sloan Digital Sky Survey, an ambitious project to map much of the sky. Citizen science volunteers gave the objects their colorful name. Their greenish hue is because most of their light comes from glowing gas clouds, rather than directly from stars.
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These galaxies are rare in the present-day universe. Astronomers think that the ones that do exist are analogs of galaxies that were more plentiful in the early universe.
“They’re a bit like living fossils,” said astrophysicist James Rhoads of NASA’s Goddard Space Flight Center in Greenbelt, Md. “Coelacanths, if you will,” referencing a fish thought to be extinct until it showed up off the coast of South Africa in 1938 (SN: 12/2/11).
These galaxies leak much more ultraviolet light, which can rip electrons from atoms, than typical galaxies do. So Green Peas dating to the universe’s first billion years or so could be partly responsible for a dramatic and mysterious cosmic transition called reionization, when most of the hydrogen atoms in the early universe had their electrons torn away (SN: 1/7/20).
Three ancient Green Peas turned up in JWST’s first image, released in July 2022 (SN: 7/21/22). The objects look red in JWST’s infrared vision, but the wavelengths of light they emit are like those of the previously discovered Green Peas. The findings were also published in the Jan. 1 Astrophysical Journal Letters.
“This helps us explain how the universe reionized,” Rhoads said. “I think this is an important piece of the puzzle.” More
- in Humans
Remnants of Ancient Life review: Explore the palaeobiology revolution
Dale Greenwalt’s book is a gripping look at palaeobiology, a field achieving incredible insights into ancient life on Earth
Humans
11 January 2023
By Simon Ings
The palaeontology collection at the Smithsonian’s National Museum of Natural Historychip clark/museum of natural history
Remnants of Ancient Life
Dale Greenwalt (Princeton University Press)
WHAT is a fossil made of? Mineralised rocky fossils are what first spring to mind, but others, like the fossils of the Burgess Shale in Canada, are made of pure carbon and can be thought of as proto-coal. There are also tantalising Cretaceous insects preserved in amber.
Whatever they are made of, fossils contain treasures. The first really good microscopic study of mineralised dinosaur bone was able to reveal its … More - in Humans
The best video games out in 2023
Brain training apps claim to make us smarter, but there is no evidenceThere are plenty of apps that offer mental exercises claiming to make users smarter the more they play. Not only are they not much fun, but studies show they have no effect on performance, says Adrian Hon More
- in Humans
How to force your rhubarb for an earlier, sweeter crop
Depriving rhubarb plants of light for several weeks forces them to grow fast and gives an earlier harvest, says Clare Wilson
Humans
11 January 2023
By Clare Wilson
GAP Photos/Clive Nichols
I HAVE just finished one of the few winter jobs at my allotment: preparing my rhubarb patch, including setting up one of the plants to be forced. This means covering it with a large container to make the stalks grow more quickly in search of light.
If you have the space, I highly recommend getting a few rhubarb plants as they are so easy to grow. I give mine little attention, but each spring they produce a huge crop when there isn’t much home-grown produce around. Technically, rhubarb stems are a vegetable as they are the plant’s leaf stalks, but … More - in Humans
Don’t Miss: Reading up on Quantum Theory, As Simply As Possible
New Scientist’s weekly round-up of the best books, films, TV series, games and more that you shouldn’t miss
Humans
11 January 2023
Read
Quantum Field Theory, As Simply As Possible is delivered with humour and erudition by Anthony Zee. What better way to get the little grey cells going than by unifying quantum mechanics and special relativity? On sale from 17 January.
NASA/JPL-Caltech
Watch
Hearing the Light is a talk by Clara Brasseur about representing telescope data as sound, also called astronomical data sonification. Listen to real data from the Kepler Space Telescope (pictured above) in her online talk on 20 January at 7.30pm GMT.Read
Cold People struggle to … More - in Humans
Why it is important to explore the outer limits of knowledge
Science and reason generate reliable knowledge about the world, but they have their limits. Exploring them can shed light on what knowledge really is, and should help us gain more of it
Humans
| Leader
11 January 2023
Lagano/Shutterstock
SCIENCE is the culmination of humanity’s attempts to reason about the world. It produces knowledge in a reliable way, and it has done so with great success. It has revealed many of nature’s secrets, from the molecular machinery inside cells to the grand scheme of how the universe began and evolved to what we see today. But for all their undoubted achievements, science and reason have their constraints.
Our species is unique (as far as we know) in its ability to know what we don’t know. That alone might make us duty bound to explore the limits of knowledge and … More Methylated gases could be an unambiguous indicator of alien life
SEATTLE — Attention alien hunters: If you want to find life on distant planets, try looking for signs of toxic chemical cleanup.
Gases that organisms produce as they tidy up their environments could provide clear signs of life on planets orbiting other stars, researchers announced January 9 at the American Astronomical Society meeting. All we need to do to find hints of alien life is to look for those gases in the atmospheres of those exoplanets, in images coming from the James Webb Space Telescope or other observatories that could come online soon.
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Barring an interstellar radio broadcast, the chemistry of a remote planet is one of the more promising ways that researchers could detect extraterrestrial life. On Earth, life produces lots of chemicals that alter the atmosphere: Plants churn out oxygen, for example, and a host of animals and plants release methane. Life elsewhere in the galaxy might do the same thing, leaving a chemical signature humans could detect from afar (SN: 9/30/21).
But many of life’s gases are also released in processes that have nothing to do with life at all. Their detection could lead to the false impression of a living planet in a faraway solar system, when it’s really just a sterile rock.
At least one type of compound that some organisms produce to protect themselves from toxic elements, however, might provide unambiguous indications of life.
The life-affirming compounds are called methylated gases. Microbes, fungi, algae and plants are among the terrestrial organisms that create the chemicals by linking carbon and hydrogen atoms to toxic materials such as chlorine or bromine. The resulting compounds evaporate, sweeping the deadly elements away.
The fact that living creatures almost always have a hand in making methylated gases means the presence of the compounds in a planet’s atmosphere would be a strong sign of life of some kind, planetary astrobiologist Michaela Leung of the University of California, Riverside said at the meeting.
The same isn’t true of oxygen and methane. Oxygen, in particular, can accumulate when a hot star warms a planet’s oceans. “You have a steam atmosphere, and the [ultraviolet] radiation from the star splits up the water” into its constituent parts, oxygen and hydrogen, Leung says. Hydrogen is light, so much of it is lost to space on small planets. “What you have left is all of this oxygen,” which, she says, leads to “really convincing oxygen signals in this process that at no point involved life.”
Similarly, while living organisms produce methane in abundance, lifeless geological phenomena like volcanoes do too.
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At the concentrations of methylated gases typical of Earth, these gases will be hard to see in the atmospheres of distant planets, even with an instrument as powerful as the Webb telescope (SN: 12/20/22). But Leung has reason to believe there may be planets where the gas abundance is thousands of times that of Earth.
“The most productive environments [for releasing methylated gases] that we see here on Earth,” she says, “are things like estuaries and wetlands.” A watery planet with lots of small continents and correspondingly more coastline, for example, could be packed with organisms cleaning away toxic chemicals with methylated gases.
One of the benefits of looking for the compounds as a sign of life is that it doesn’t require that the life resembles anything like what we have on our planet. “Maybe it’s not DNA-based, maybe it has other weird chemistry going on,” Leung says. But by assuming chlorine and bromine are likely to be toxic generally, methylated gases offer what Leung calls an agnostic biosignature, which can tell us that something is alive on a planet even if it’s utterly alien to us.
“The more signs of life we know to look for, then the better our chances of recognizing life when we do encounter it,” says Vikki Meadows, an astrobiologist at the University of Washington in Seattle who was not involved with the study. “It also helps us understand what kind of telescopes we should build, what we should look for and what the instrument requirements should be. Michaela’s work is really important for that reason.” More
