The strangest thing about a blue whale’s heart is not its bulk. It is how close that heart comes to stopping. On a deep foraging dive, the largest heart on the planet can slow to as few as two beats a minute, a pace so far below what physiology predicts for an animal that size that it looks, at first, like an error in the data.
It was not an error. In 2019, a team led by Stanford’s Jeremy Goldbogen, with Paul Ponganis of the Scripps Institution of Oceanography as senior author, made the first recording of a blue whale’s heart rate in the wild. What they found raised a question the whale’s size alone never could: how does a heart that big run that slow, then race back so fast, dive after dive, without faltering?
Carefully, and with a long pole. Working in Monterey Bay, co-author David Cade attached a suction-cup electrocardiogram tag near the left flipper of a male blue whale estimated to be about 15 years old. The tag, roughly the size of a lunchbox, was held by four suction cups, two carrying the electrodes that picked up the electrical signal of the heart.
It stayed on for about 8.5 hours of diving before detaching and floating up to be retrieved. The team almost did not believe what came back. “We had no idea that this would work and we were skeptical even when we saw the initial data,” Goldbogen said. Reading the trace was its own task. “With a very keen eye, Paul Ponganis … found the first heart beats in the data,” he recalled. Goldbogen later told Smithsonian the whole attempt felt unlikely: “I honestly thought it was a long shot because we had to get so many things right.”
The results were published on 25 November 2019 in Proceedings of the National Academy of Sciences, under a title that named the puzzle directly: extreme bradycardia and tachycardia in the world’s largest animal. This is a single animal measured once in the field, not a survey of the species, so the pattern is best read as a first window rather than a settled rule.
A heart swinging between two extremes on every dive. During dives that reached as deep as 184 metres and lasted up to 16.5 minutes, the heart rate typically settled to four to eight beats a minute and bottomed out at just two beats per minute. For a body this large, the predicted resting rate is closer to 15 beats per minute, so the diving heart was running far below what its size alone would suggest.
Then came the reversal. The moment the whale returned to the surface to breathe and re-oxygenate, the heart climbed to its highest recorded rate of 30 to 37 beats per minute. There was one wrinkle even at depth. During a lunge to feed, the rate briefly jumped to about 2.5 times the dive minimum, before sinking again.
The slow pace is oxygen management. Holding a single breath through a long dive, the whale conserves its limited oxygen by dropping its heart rate and routing blood to the organs that need it most, the same dive response seen across diving mammals, scaled up to the largest body on Earth. The surface surge is the repayment, the heart racing to reload oxygen before the next plunge.
What struck the team was how little headroom remained. The surface rate sat near the whale’s estimated physiological maximum, which led them to suspect the heart may already be working at its functional ceiling. That ceiling, set by body size and the demands of lunge feeding, “can help us understand biological limits to size,” Goldbogen said. The idea that a maxed-out heart is one reason blue whales never grew larger is the team’s hypothesis, not a proven fact, and they have been clear that much more work is needed to test it.
Probably not. The comparison is repeated everywhere, but it does not survive a close look at an actual specimen. A preserved blue whale heart weighed roughly 400 pounds, while National Geographic noted that a Volkswagen Beetle weighs around 3,000 pounds, which makes the car framing closer to legend than measurement. A researcher’s suggestion of a small golf cart is nearer the mark, though even that overshoots, since golf carts run heavier than the heart itself. The simpler version holds: it is the largest heart of any animal, and its size is not the most interesting thing about it.
What makes the 2019 recording matter is the method as much as the numbers. One tag, one whale, 8.5 hours. The questions the data invites next are the ones that take a fleet of recordings to answer: whether the same cardiac swing holds across larger and smaller individuals, whether it shifts with feeding, depth, or age, and how close other giants of the ocean run to their own limits. The first beat was the hard part. What it measures next is still open.
The post A blue whale has the largest heart of any animal, but the first recording ever made of one beating revealed something stranger than its size: on a deep foraging dive the heart can slow to as few as 2 beats a minute, then race back toward 37 the instant the whale surfaces to breathe appeared first on Space Daily.
On June 19, 2004, at the Kitt Peak National Observatory in Tucson, Arizona, astronomers Roy Tucker, David Tholen, and Fabrizio Bernardi discovered Asteroid Apophis. This Near-Earth Object (NEO), approximately 1,099 to 1,230 feet (335 to 375 meters) wide, reached the highest ever rating of level 4 out of 10 on the Torino Impact Hazard Scale,Continue reading "June 19, 2004: Astroid Apophis is discovered"
The post June 19, 2004: Astroid Apophis is discovered appeared first on Astronomy Magazine.
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Last year, NASA's Lucy spacecraft encountered a bi-lobed asteroid that is a chunk of an even larger rocky body that was smashed apart in an almighty collision 155 million years ago. This little pitstop happened on Lucy's way to a rendezvous with the Trojan asteroids that shadow Jupiter around the sun.
The asteroid 52246 Donaldjohanson, better known as "DJ" to Lucy's mission scientists and named after the paleoanthropologist who discovered the Lucy hominin fossil in Ethiopia in 1974, orbits the sun in the inner part of the main asteroid belt between Mars and Jupiter.
The true Lucy fossil dates back in time 3.2 million years and is an important link in the evolutionary chain that led to homo sapiens. Likewise, primitive asteroidal bodies are somewhat like fossilized remnants of the building blocks of the solar system's planets, including Earth. Understanding the make-up of these asteroids and where they formed versus where they are now can provide crucial insights into how Earth was assembled and where its organic materials and water may have come from.
Lucy flew past DJ in April of 2025. It is a pretty primitive asteroid, meaning that it has, or once upon a time had, certain volatile materials such as water-ice, as well as plenty of carbon — all things that can be removed thermally over time. Most objects that contain volatiles originate in the outer solar system, where it is cold enough that the volatiles do not sublimate away.
Within DJ's composition, Lucy detected iron-bearing phyllosilicates, which are a mineral formed in the presence of liquid water.
"Phyllosilicates are an indication that water was present and there was some degree of aqueous alteration," Simone Marchi, a planetary scientist from the South-west Research Institute and lead of the study into DJ, told Space.com.
However, for DJ to have had water, it must have formed further out from the sun, possibly in the outer asteroid belt.
"But DJ belongs to the inner asteroid belt so that's already intriguing," said Marchi.
The spectral evidence also indicates DJ was only partially altered by water, which Marchi says tells us something about its history.
"The aqueous alteration terminated early, and though we don't know why, we can speculate. In order to have aqueous alteration there needs to be some internal heating [usually via radioactive elements] and if something forms later than everything else then there will be less heat [since many of the radioactive elements will have already decayed]. Or perhaps there was just less water to start with where it formed."
What we do know is that DJ was once part of a much larger asteroid that suffered a giant impact 155 million years ago, causing the parent body to break apart into a number of chunks, the largest being the 45-mile-wide (73-kilometer-wide) asteroid 163 Erigone. Consequently, the remains of this parent asteroid, including DJ, are collectively referred to as the Erigone family.
DJ's violent origin may also explain its shape, which features two lobes joined together by a narrower and relatively smooth neck.
"We have now seen many small bodies in the solar system that appear to have this bi-lobed shape, and that's across a wide range of sizes," said Marchi.
For example the near-Earth asteroids 25142 Itokawa, which was visited by the first Japanese Hayabusa mission in 2005, and 4149 Toutatis that was encountered by China's Chang'e 2 in 2012, are both bi-lobed. So too is the tiny asteroid Selam, which is a satellite of the asteroid 152830 Dinkinesh visited by Lucy in 2023. Then there are cometary bodies including 67P Churyumov–Gerasimenko visited by the Rosetta mission and comet 19P/Borrelly, imaged by NASA's Deep Space 1 spacecraft in 1999.
These objects are all different sizes, different types and in different locations, but they all share the same structure. However, Marchi cautions that they might not all form the same way. For example, the neck between the lobes of comets such as 67P might form through erosion via sublimation and outgassing as the comet gets closer to the Sun, whereas for asteroids it might indicate a history of being involved in a giant impact, the resulting fragments coming together to be bound by gravity – a so-called contact binary.
Lucy now continues onwards, scheduled to encounter its first trojan asteroid, known as 3548 Eurybates, in August 2027. Trojans are asteroids that have been captured by Jupiter's gravity at the L3 and L4 Lagrange points, 60 degrees in front and 60 degrees behind Jupiter itself.
"We think that the Trojans, based on our understanding of the solar system, formed further out and then were captured where they are today following the early shuffling of the planets," said Marchi. "This shuffling could also have been the origin of DJ, so there could be a connection there between DJ and the Trojans."
Compositionally, the majority of trojans are expected to be even more primitive than DJ, containing more carbon, water and other volatile materials that would sublimate if they got too close to the sun.
That is all except one: Eurybates.
"It is the only one of our targets that from spectroscopy appears to be relatively similar to DJ. It's not identical, but it is closer in composition to DJ than the other Trojans, so it will be intriguing to compare them," said Marchi.
Indeed, any similarities will help tell us how asteroids were herded around during the first few hundred million years of solar system history following the formation of the planets. Jupiter and Saturn, especially, began migrating inwards and then out again. In doing so, their gravity pushed and pulled minor bodies all over the place, as did the gravity of Uranus and particularly Neptune as they edged outwards. These migrations led to the formation of the asteroid belt and the Kuiper belt, and ejected trillions of bodies into the wide orbits of the Oort Cloud.
"The key question is, if DJ has been relocated in the inner asteroid belt, then how many other asteroids came along with it and ended up being closer to the Earth, where they could have delivered some water, some organics and other things to our planet?" asked Marchi.
Lucy will visit six of Jupiter's trojans, which in total number over 15,300 discovered so far. Far from lumps of rock, the trojans, along with DJ and Dinkinesh (which is the Ethiopian name for the Lucy fossil), are windows into the past, and the storytellers of the Earth's most ancient history.
Lucy's findings from Donaldjohanson were published on Thursday (June 18) in the journal Science.
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