Each year, scientists break new ground in their quest to understand life and the mysteries of the cosmos. Here are eight milestones in 2024 that caught our attention

Reading a fruit fly’s mind

The first complete map of a fruit fly’s brain details all 139,255 nerve cells and the 54.5 million connections between them. It’s the largest brain map made of any animal, even though the fruit fly’s brain is poppy seed–sized (SN: 11/2/24, p. 32). The map could lead to a deeper understanding of how information flows in the brain.

Nuclear timekeeping

Scientific clockmakers debuted the world’s first prototype nuclear clock. Nuclear clocks would base time on fluctuating energy levels in atomic nuclei. While the prototype isn’t a fully oper­ational timepiece, its development showed scientists the precise frequency of light required to set off fluctuations in the energy levels of atomic nuclei (SN: 10/5/24, p. 7). Nuclear clocks could help scientists explore fundamental physics — an area of science teeming with potential discovery.

Panda protection

Giant panda biology took a huge leap forward this year: For the first time, researchers transformed the bear’s skin cells into stem cells that can be coaxed into any other type of cell in the body (SN: 10/19/24, p. 10). Being able to take skin cells and end up with, say, the precursors of sperm and egg cells gives conservationists a leg up in defending giant pandas from extinction by boosting breeding and expanding the bear’s small gene pool.

New nitrogen factory

A eukaryote has joined some bacteria and archaea in the nitrogen fixation club. A type of marine alga has an internal factory that transforms nitrogen into ammonia, a biologically usable form (SN: 4/11/24). The factory probably started as a separate life-form that entered a symbiotic relationship with the eukaryote. Over millennia, the two may have become so intertwined that they became one organism.

Ultrarare decay

By smashing protons into a fixed target, physicists witnessed a predicted but never-before-confirmed form of particle decay (SN: 10/19/24, p. 16). The collision produced subatomic particles called kaons. Those kaons decayed into an uncommon combination of three other types of particles at a rate of about 13 in 100 billion times. Continued investigation into the decay might help unveil new physics.

Recycling dead weight

The Cyathea rojasiana tree fern is the first plant known to turn its dead leaves into roots (SN: 2/24/24, p. 5). The leaves sprout rootlets, which the fern may use to search out nutrients in the soil of Panamanian forests. Researchers now want to figure out how the rootlets absorb nutrients.

Black hole awakening

In a sleepy galaxy not too far away, a supermassive black hole appears to be gradually waking up, providing astrophysicists with their first peek of a black hole transitioning from dim and quiet to bright and active (SN: 7/13/24 & 7/27/24, p. 7). When supermassive black holes consume material such as stars, they usually glow for only a few days to weeks. But lucky for scientists, this black hole has remained luminous for years. While researchers are not completely certain why the black hole continues to glow, they’re following the situation closely and hoping to glean some insights into how black holes grow.

Quantum physics versus the speed of Earth

The rate of Earth’s rotation is well established, but scientists measured it in a new way, using entangled quantum particles (SN: 7/14/24 & 7/28/24, p. 5). The theories of quantum physics and gravity are largely incompatible, so it was noteworthy that the experiment’s measurements aligned with Earth’s known rotation rate. Physicists hope the experiment will open doors for further research into demystifying how gravity and quantum physics interact.