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2024 was studded with record-setting scientific discoveries. From tracing the origins of glow-in-the-dark animals to developing the world’s fastest microscope, these superlative feats captured our imagination.
Ancient Airburst
Some 2.5 million years ago, an asteroid combusted in Earth’s atmosphere before it could hit the ground and leave a crater, making the event the oldest known midair explosion. That conclusion is based on a chemical analysis of nearly 120 microscopic rocks buried deep underneath Antarctic ice. The ancient pebbles are rich in olivine and spinel minerals, which suggests the specimens are the asteroid’s remnants, scientists say.
Chemical analysis of microscopic bits of rock collected in Antarctica (three shown) suggests they are consistent with a type of asteroid known as an ordinary chondrite that broke up in the atmosphere. Courtesy of Matthias van Ginneken
The dawn of photosynthesis
Microfossils in Australia harbor the oldest evidence of photosynthesis. Fossilized bacteria dating to about 1.75 billion years ago preserve structures that resemble thylakoid membranes, which help modern cyanobacteria convert sunlight into oxygen. Scientists had previously suspected that cyanobacteria were photosynthesizing way back then, but the new finding is the first direct evidence.
Researchers found microscopic fossils of cyanobacteria dubbed Navifusa majensis (left) in 1.73 billion- to 1.78 billion-year-old shale from Australia). A peek inside the fossils revealed black horizontal lines indicating the bacterium contained stacks of membranes known as thylakoids (right) like those in modern bacteria and plants where oxygen-producing photosynthesis takes place.C.F. Demoulin, et al./Nature 2024
Fastest backflip
Dicyrtomina minuta springtails can launch themselves up to 60 millimeters in the air and spin at a rate of up to 368 times per second, making the arthropods the fastest known backflippers (SN: 10/5/24, p. 4). An appendage on the underbelly helps the miniature gymnasts lift off while another helps them stick the landing.
Backflipping arthropods called globular springtails can vault themselves up to 60 millimeters high and spin up to 29 times in the blink of an eye. Two springtails jump off a platform in a lab in this high-speed camera footage.A. Smith
Wee-est frog
At just 6.5 millimeters long, a Brazilian flea toad (Brachycephalus pulex) has been crowned the world’s smallest known frog (SN: 3/23/24, p. 4). Petite enough to sit on a pinkie fingernail, the amphibian beat the previous champion by about a millimeter.
The Brazilian flea toad has nabbed the title of world’s smallest known amphibian and smallest known vertebrate. At just 7 millimeters long on average, the frogs are a fraction the size of a 27-millimeter-wide $1 Brazilian real coin.W.H. Bolaños, I.R. Dias and M. Solé/Zoologica Scripta 2024
Large genome, small package
The largest known genetic instruction manual belongs to a tiny fern (SN: 6/29/24, p. 4). Tmesipteris oblanceolata is 15 centimeters long but possesses a genome that is 50 times as large as humans’. If unraveled, the fern’s spool of DNA would stretch 100 meters long, scientists say.
The yellow balls on this New Caledonian fork fern are synangia, the spore-producing structures in this group of ferns. Oriane Hidalgo
Oldest bioluminescence
Bioluminescence has a new birthday. Ancestors of a group of deep-sea corals glowed in the dark 540 million years ago, scientists say. Scientists had thought that animal bioluminescence began about 267 million years ago in an ancestor of sea fireflies — tiny, seed-shaped crustaceans.
Colonial false gold coral (Savalia) demonstrates its bioluminescence on a Bahamian reef. This form of bioluminescence in octocorals is the oldest yet dated.Sönke Johnsen
Supersmall knot
Knots come in all shapes and sizes. Small figure-eight knots hold people as they scale cliffs. Bigger bowlines secure ships to shore. This year, scientists designed the smallest and tightest knot yet (SN: 2/24/24, p. 4). This trefoil knot is made from a string of 54 gold, phosphorus, oxygen and carbon atoms that is pretzeled over itself three times.
In this simplified illustration of the smallest known molecular knot, a chain of 54 gold (red), phosphorus (purple), oxygen (mauve) and carbon (black) atoms crosses itself three times to form a pretzel-like shape.Z. Li et al/Nature Communications 2024
