Jupiter’s moon Europa was captured by the JunoCam instrument aboard NASA’s Juno spacecraft during the mission’s close flyby on Sept. 29, 2022. The images show the fractures, ridges, and bands that crisscross the moon’s surface. Credit: NASA/JPL-Caltech/SwRI/MSSS; Image processing: Björn Jónsson (CC BY 3.0)
Images from the JunoCam visible-light camera aboard NASA’s Juno spacecraft supports the theory that the icy crust at the north and south poles of Jupiter’s moon Europa is not where it used to be. Another high-resolution picture of the icy moon, by the spacecraft’s Stellar Reference Unit (SRU), reveals signs of possible plume activity and an area of ice shell disruption where brine may have recently bubbled to the surface.
The JunoCam results recently appeared in the Planetary Science Journal and the SRU results in the journal JGR Planets.
On Sept. 29, 2022, Juno made its closest flyby of Europa, coming within 220 miles (355 kilometers) of the moon’s frozen surface. The four pictures taken by JunoCam and one by the SRU are the first high-resolution images of Europa since Galileo’s last flyby in 2000.
This black and white image of Europa’s surface was taken by the Stellar Reference Unit aboard NASA’s Juno spacecraft durring the Sept. 29, 2022 flyby. The chaos feature names “The Platypus” is seen in the lower right corner. Credit: NASA/JPL-Caltech/SwRI
Europa Clipper’s focus is on Europa—including investigating whether the icy moon could have conditions suitable for life. It is scheduled to launch on the fall of 2024 and arrive at Jupiter in 2030. Juice (Jupiter Icy Moons Explorer) launched on April 14, 2023. The ESA mission will reach Jupiter in July 2031 to study many targets (Jupiter’s three large icy moons, as well as fiery Io and smaller moons, along with the planet’s atmosphere, magnetosphere, and rings) with a special focus on Ganymede.
Although Mars presents a barren, dusty landscape with no signs of life so far, its geological features such as deltas, lakebeds, and river valleys strongly suggest a past where water once flowed abundantly on its surface. To explore this possibility, scientists examine sediments preserved near these formations. The composition of these sediments holds clues about the early environmental conditions, the processes that shaped the planet over time, and even potential signs of past life.
In one such analysis, sediments collected by the Curiosity rover from Gale Crater, believed to be an ancient lake formed approximately 3.8 billion years ago due to an asteroid impact, revealed organic matter. However, this organic matter had a significantly lower amount of the carbon-13 isotope (13C) relative to carbon-12 isotopes (12C) compared to what is found on Earth, suggesting different processes of organic matter formation on Mars.
“If the estimation in this research is correct, there may be an unexpected amount of organic material present in Martian sediments. This suggests that future explorations of Mars might uncover large quantities of organic matter,” says Ueno.
More information: Yuichiro Ueno et al, Synthesis of 13C-depleted organic matter from CO in a reducing early Martian atmosphere, Nature Geoscience (2024). DOI: 10.1038/s41561-024-01443-z
Space scientists led by the University of Leicester have combined evidence from simulations, observations and analysis of meteorites to recreate the orbital instability caused as the giant planets of our solar system moved into their current locations, known for 20 years as the Nice model.
The findings are published in the journal Science and presented at the European Geological Union General Assembly in Vienna.
At the beginning of the solar system, the giant planets—Jupiter, Saturn, Uranus, and Neptune—had more circular and more compact orbits than they do today. Previous research has established that orbital instability in the solar system changed that orbital configuration and caused smaller planetesimals to be dispersed. Many of these collided with the inner terrestrial planets in what scientists have termed the Late Heavy Bombardment.
Lead author Dr. Chrysa Avdellidou from the University of Leicester School of Physics and Astronomy said, “The question is, when did it happen? The orbits of these planets destabilized due to some dynamical processes and then took their final positions that we see today. Each timing has a different implication, and it has been a great matter of debate in the community.”
“What we have tried to do with this work is to not only do a pure dynamical study but combine different types of studies, linking observations, dynamical simulations, and studies of meteorites.”
They focused on a type of meteorite known as enstatite chondrites, which have a very similar composition to Earth and very similar isotopic ratios, which means they were formed in our neighborhood. By making spectroscopic observations using ground-based telescopes, they linked those meteorites to their source: a family of fragments in the asteroid belt known as Athor.
This suggests that Athor was originally much larger and formed closer to the sun and that it suffered a collision that reduced its size out of the asteroid belt.
To explain how Athor ended up in the asteroid belt, the scientists tested various scenarios using dynamical simulations, concluding that the most likely explanation was the gravitational instability that shifted the giant planets to their current orbits. Analysis of the meteorites showed that this occurred no earlier than 60 million years after the solar system began to form.
Previous evidence from asteroids in Jupiter’s orbit has also put constraints on how late this event occurred, with scientists concluding that the gravitational instability must have occurred between 60 and 100 million years after the birth of the solar system, 4.56 billion years ago.
Previous evidence has shown that Earth’s moon was formed during this period, with one hypothesis being that a planetesimal known as Theia collided with Earth, and debris from that collision formed the moon.
Timing of the orbital instability is important as it determines when some of the familiar features of our solar system would develop—and may even have had an impact on the habitability of our planet.
Dr. Avdellidou added, “It’s like you have a puzzle, you understand that something should have happened, and you try to put events in the correct order to make the picture that you see today. The novelty with the study is that we are not only doing pure dynamical simulations, or only experiments, or only telescopic observations.”
“There were once five inner planets in our solar system and not four, so that could have implications for other things, like how we form habitable planets. Questions like, when exactly did objects come delivering volatile organics to our planet to Earth and Mars?”
Marco Delbo, co-author of the study and Director of Research at Nice Observatory in France, said, “The timing is very important because a lot of planetesimals populated our solar system at the beginning. And the instability clears them, so if that happens 10 million years after the beginning of the solar system, you clear the planetesimals immediately, whereas if you do it after 60 million years, you have more time to bring materials to Earth and Mars.”
More information: Chrysa Avdellidou et al, Dating the Solar System’s giant planet orbital instability using enstatite meteorites, Science (2024). DOI: 10.1126/science.adg8092
(turn up resolution (up to 8k HD) and turn down (or off) volume before playing) (also viewable in 3D)
Researchers have used the Dark Energy Spectroscopic Instrument to make the largest 3D map of our [local] universe and world-leading measurements of dark energy, the mysterious cause of its accelerating expansion. source. Longer 22 minute video on this endeavor.
Sometime between now and September, a massive explosion 3,000 light years from Earth will flare up in the night sky, giving amateur astronomers a once-in-a-lifetime chance to witness this space oddity.
The binary star system in the constellation Corona Borealis—”northern crown”—is normally too dim to see with the naked eye.
But every 80 years or so, exchanges between its two stars, which are locked in a deadly embrace, spark a runaway nuclear explosion.
The light from the blast travels through the cosmos and makes it appear as if a new star—as bright as the North Star, according to NASA—has suddenly just popped up in our night sky for a few days.
It will be at least the third time that humans have witnessed this event, which was first discovered by Irish polymath John Birmingham in 1866, then reappeared in 1946.
The appropriately named Sumner Starrfield, an astronomer at Arizona State University, told AFP he was very excited to see the nova’s “outburst”.
After all, he has worked on T Coronae Borealis—also known as the “Blaze Star”—on and off since the 1960s.
Starrfield is currently rushing to finish a scientific paper predicting what astronomers will find out about the recurring nova whenever it shows up in the next five months.
“I could be today… but I hope it’s not,” he said with a laugh.
The white dwarf and red giant
There are only around 10 recurring novas in the Milky Way and surrounding galaxies, Starrfield explained.
Normal novas explode “maybe every 100,000 years,” he said. But recurrent novas repeat their outbursts on a human timeline because of a peculiar relationship between their two stars.
One is a cool dying star called a red giant, which has burnt through its hydrogen and has hugely expanded—a fate that is awaiting our own sun in around five billion years.
The other is a white dwarf, a later stage in the death of a star, after all the atmosphere has blown away and only the incredibly dense core remains.
Their size disparity is so huge that it takes T Coronae Borealis’s white dwarf 227 days to orbit its red giant, Starrfield said.
The two are so close that matter being ejected by the red giant collects near the surface of the white dwarf.
Once the mass roughly of Earth has built up on the white dwarf—which takes around 80 years—it heats up enough to kickstart a runaway thermonuclear reaction, Starrfield said.
This ends up in a “big explosion and within a few seconds the temperature goes up 100-200 million degrees” Celsius, said Joachim Krautter, a retired German astronomer who has studied the nova.
The James Webb space telescope will be just one of the many eyes that turn towards the outburst of T Coronae Borealis once it begins, Krautter told AFP.
But you do not need such advanced technology to witness this rare event—whenever it may happen.
“You simply have to go out and look in the direction of the Corona Borealis,” Krautter said.
Some lucky sky gazers are already preparing for the year’s biggest astronomic event on Monday, when a rare total solar eclipse will occur across a strip of the United States.
In a world first, a cosmic ‘speed camera’ just revealed the staggering speed of neutron star jets
March 31st, 2024
How fast can a neutron star drive powerful jets into space? The answer, it turns out, is about one-third the speed of light, as our team has just revealed in a new study published in Nature.
Energetic cosmic beams known as jets are seen throughout our universe. They are launched when material—mainly dust and gas—falls in towards any dense central object, such as a neutron star (an extremely dense remnant of a once-massive star) or a black hole.
The jets carry away some of the gravitational energy released by the infalling gas, recycling it back into the surroundings on far larger scales.
The most powerful jets in the universe come from the biggest black holes at the centers of galaxies. The energy output of these jets can affect the evolution of an entire galaxy, or even a galaxy cluster. This makes jets a critical, yet intriguing, component of our universe.
Interestingly, the jet speed we measured was close to the “escape speed” from a neutron star. On Earth, this escape speed is 11.2 kilometers per second—what rockets need to achieve to break free of Earth’s gravity. For a neutron star, that value is around half the speed of light.
FIGU Bulletin Date: June 1996 (English Edition: February 1998)
DISCOVERIES IN SPACE
As early as December 1995, astronomers noticed a mysterious object in space which sent strong X-ray signals into the universe every hour, in a way similar to a light house. First mention regarding these suspiciously regular radio signals was offered in 1968, when British astronomers became capable of picking up such signals. Headlines at the time read “Contact Made with Little Green Men,” for everyone was convinced that only an extraterrestrial intelligence could transmit such signals in a regular pattern. It was not long, however, before theoretical astrophysicists found a less spectacular, yet no less fascinating explanation for the phenomenon, namely, that the signals were sent by a rapidly rotating remnant of a collapsed star, a pulsating radio star — a pulsar. Early in December 1995, astronomers discovered a new type of pulsar in the vicinity of the Milky Way’s center that emits light within the more energetic, shorter-waved X-ray range. Approximately every hour the pulsar sends out an enormous X-ray pulse. The pulsar was detected by a research satellite specifically constructed for the purpose of examining long-observed X-ray flashes, which occasionally and unexpectedly flare up in the universe only to immediately subside again.
The newly discovered pulsar initially sent its X-ray flashes at one-second intervals, then every few minutes, and after two days then once an hour. Thereafter it entered an odd pattern of behavior displaying several variations which were previously attributed to various celestial objects. Currently this pulsar is the strongest known X-ray source in the sky.
At this point, mystery surrounds the mechanism by which these rhythmic X-ray flashes occur; but this much we do know: This cosmic X-ray light house is a dual-star system comprising a small neutron star of immense mass and a lighter-weight companion star. It is presumed that the lighter star intermittently loses some of its matter, while the neutron star “siphons” it off. This process causes the material to accelerate to approximately 150,000 kilometers/ sec. [93,750 mps], or half the speed of light. Thereupon, the material crashes to the surface of the neutron star, generating a temperature of approximately 1 billion degrees Celsius [1.8 billion F], hot enough to discharge X-ray flashes one million times brighter than our sun.
Billy
Artists depiction of Nuclear explosions on a neutron star feed its jets. Credit: Danielle Futselaar and Nathalie Degenaar, Anton Pannekoek Institute, University of Amsterdam, CC BY-SA
Additional information:
March 3rd, 2012. CR 537
Billy:
I do not doubt it either. But something else: On the 27th of December 2004, a powerful flash of energy from outer space was registered, and already about 450 million years ago, the Earth was hit by a flash of energy, or a gamma ray, respectively, which was not very strong, but it did a lot of harm, as Quetzal explained to me. What I am interested in is what actually happens when a very strong flash of gamma lightning respectively gamma radiation hits the Earth, and how does such a flash of energy come about, if you can explain the whole thing a bit simply?
Ptaah:
31. Gamma ray flashes have an extremely destructive effect when they hit planets.
32. If, for example, the Earth were struck with the full energy of a gigantic flash of gamma radiation, the origin of which would be far less than 10 million light-years away, then the Earth’s atmosphere as well as all electrical and electronic equipment would be completely destroyed and all life would be wiped out.
33. The phenomena of such high-energy flashes, as you call them, have various causes; for example, gamma-ray bursts are caused by a nuclear collapse of massive suns, but also by the fusion of two neutron stars, or by the fusion of a neutron star with a black hole in an extragalactic star system.
December 2nd, 1987. CR 220
Billy:
Nice outlooks. So let’s talk about something else. I still have a question regarding neutron stars, which exhibit the greatest density in matter, as our scientists say. A thimble full of such a neutron star should weigh, as they say, about a billion (1,000,000,000) tons. I would like to ask whether they have not made a mistake in the weight, for I find a billion (1,000,000,000) tons somewhat steep.
Quetzal:
55. Nevertheless, it is of correctness.
56. However, it is to be rectified that neutron stars do not exhibit the densest and heaviest mass but rather other objects in the material Universe.
57. The matter of these tremendously heavier objects is also of a different kind than what is known to the earthly physical scientists and astrophysical scientists as well as astrophysical chemists.
Billy:
Aha, and what do you call these objects, and at the same time, does it concern stars?
Quetzal:
58. The second part of your question is to be affirmed in the way that, as a rule, it concerns former stars, so collapsed solar structures.
59. But still, such objects also exist in the form of still active suns.
60. We call the collapsed structures ‘Meton-Darthelos’, which translated into your language means ‘Dark Heavy Suns’.
61. We call the still active suns of this kind ‘Saten-Darthelos’, so ‘Radiant Heavy Suns’ or ‘Active Heavy Suns’.
62. These names correspond to traditions from very early times of our people.
A Mount Everest-sized ‘devil’ comet making its first visit to the inner solar system in more than 70 years could be visible to the naked eye over the next few weeks.
The once or possibly twice-in-a-lifetime object, known as 12P/Pons-Brooks, is due to make its closest approach to the sun on 21 April, which is when it will be at its brightest.
For those in the northern hemisphere, the Halley-type comet is likely to be at its best visibility-wise between now and mid-April, although it won’t be the easiest to spot.
“Don’t expect it to be dazzlingly bright—the kind of image you see in photographs. It’s not going to be like that,” Dr. Robert Massey, deputy executive director at the Royal Astronomical Society, said in a video explainer.
“This is something that might just be visible to the naked eye if you don’t have a moon in the sky if there’s no light pollution, and if the weather is really clear, then you might stand a chance.”
“But for most of us, we’re going to need to pick up a pair of binoculars.”
He added, “Ideally, look at one of the apps you can get on your phone, showing you where things are in the sky, or a finder chart of some kind. That’ll really help you to track it down.”
“And when you see it, it’s likely to look like a sort of small, grayish fuzz, quite typical for many comets.”
“But you will have the satisfaction of knowing you’ve seen this once-in-a-lifetime object.”
Dr. Massey said stargazers should look to the west-north-west after sunset to catch a glimpse of Pons-Brooks, which completes its orbit once every 71.3 years and, therefore, won’t be visible again until 2095.
The icy body, which is thought to have a nucleus about 34km (21 miles) in diameter, was recognized as a comet in 1812. However, it was seen as far back as the 14th century.
It is named after the French astronomer Jean-Louis Pons—who discovered it in the early 19th century—and British-American astronomer William Robert Brooks, who observed it on its next orbit in 1883.
There has been plenty of interest and excitement about Pons-Brooks over the past few months, driven in part by a couple of unusual features.
Firstly, photographs of its approach have captured the comet’s “curious” green color.
“That’s because it has a molecule called dicarbon,” Dr. Massey explained. “What that does is it absorbs sunlight and re-radiates some of it with that characteristic green tinge.”
The other attribute that has piqued the interest of observers worldwide is its occasional “horned appearance,” earning Pons-Brooks the nickname “Devil Comet.”
The reason these pointy horn shapes appear is because the icy object is classed as a cryovolcanic comet, meaning it regularly erupts with dust, gases, and ice when pressure builds inside it as it is heated.
Cosmic Love 