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In a world first, NASA has crashed a spacecraft into an asteroid in an attempt to push the rocky traveler off its trajectory. The Double Asteroid Redirection Test – or DART – is meant to test one potential approach that could prevent an asteroid from colliding with Earth. David Barnhart is a professor of astronautics at the University of Southern California and director of the Space Engineering Research Center there. He watched NASA’s live stream of the successful mission and explains what is known so far.

1. What do the images show?

The first images, taken by a camera aboard DART, show the double asteroid system of Didymos – about 2,500 feet (780 meters) in diameter – being orbited by the smaller asteroid Dimorphos that is about 525 feet (160 meters) long.

As the targeting algorithm on DART locked onto Dimorphos, the craft adjusted its flight and began heading towards the smaller of the two asteroids. The image taken at 11 seconds before impact and 42 miles (68 kilometers) from Dimorphos shows the asteroid centered in the camera’s field of view. This meant that the targeting algorithm was fairly accurate and the craft would collide right at the center of Dimorphos.

The second-to-last image, taken two seconds before impact shows the rocky surface of Dimorphos, including small shadows. These shadows are interesting because they suggest that the camera aboard the DART spacecraft was seeing Dimorphos directly on but the Sun was at an angle relative to the camera. They imply the DART spacecraft was centred on its trajectory to impact Dimorphos at the moment, but it’s also possible the asteroid was slowly rotating relative to the camera.

The final photo, taken one second before impact, only shows the top slice of an image but this is incredibly exciting. The fact that NASA received only a part of the image implies that the shutter took the picture but DART, traveling at around 14,000 miles per hour (22,500 kilometers per hour) was unable to transmit the complete image before impact.

2. What was supposed to happen?

The point of the DART mission was to test whether it is possible to deflect an asteroid with a kinetic impact – by crashing something into it. NASA used the analogy of a golf cart hitting the side of an Egyptian pyramid to convey the relative difference in size between tiny DART and Dimorphos, the smaller of the two asteroids. Prior to the test, Dimorphos orbited Didymos in roughly 16 hours. NASA expects the impact to shorten Dimorphos’ orbit by about 1 percent or roughly 10 minutes. Though small, if done far enough away from Earth, a nudge like this could potentially deflect a future asteroid headed towards Earth just enough to prevent an impact.

3. What do we know already?

The last bits of data that came from the DART spacecraft right before impact show that it was on course. The fact that the images stopped transmitting after the target point was reached can only mean that the impact was a success.

While there is likely a lot of information to be learned from the images taken by DART, the world will have to wait to learn whether the deflection was also a success. Fifteen days before the impact, DART released a small satellite with a camera that was designed to document the entire impact. The small satellite’s sensors should have taken images and collected information, but given that it doesn’t have a large antenna onboard, the images will be transmitted slowly back to Earth, one by one, over the coming weeks.

4. What does the test mean for planetary defense?

I believe this test was a great proof-of-concept for many technologies that the US government has invested in over the years. And importantly, it proves that it is possible to send a craft to intercept with a minuscule target millions of miles away from Earth. From that standpoint DART has been a great success.

Over the course of the next months and years, researchers will learn just how much deflection the impact caused – and most importantly, whether this type of kinetic impact can actually move a celestial object ever so slightly at a great enough distance to prevent a future asteroid from threatening Earth.

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NASA captures a rare Uranus stellar occultation this month

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April 29, 2025

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NASA captures a rare Uranus stellar occultation this month

NASA’s astronomers got a rare chance to study Uranus when the planet moved in front of a distant star — a rare event called a “stellar occultation.” The occultation of Uranus occurred the morning of the April 7th and lasted for one hour. The occulation was visible from western North America and it was the first bright Uranian occultation since 1996. The Langley NASA Research Centre mobilised an international team of more than 30 scientists who combined observations from 18 observatories to gather important facts. The contribution of these two groups, together, led to phase coverage being restored and was key to the possibility of investigating the vertical structure of its atmosphere.

NASA’s Rare Uranus Occultation Unlocks New Atmospheric and Ring Discoveries

According to Space.com, planetary scientist William Saunders stressed the enormity of the effort and that it could not have been accomplished without the help of every telescope. “By observing this occultation from so many large telescopes at so many altitudes, we can determine the temperature structure of Uranus’ atmosphere at a level of detail that was not possible before,” Saunders stated. As per NASA’s official release, the newly gathered data could significantly advance plans for future Uranus exploration missions.

During the occultation, researchers measured the temperatures and chemical composition of Uranus’ stratosphere, capturing changes unseen since the last event nearly three decades ago. Uranus is about 2 billion miles (3.2 billion kilometres) from Earth. Uranus has no firm surface; rather, it is covered by a swirling mass of water, ammonia, and methane clouds. This low-freezing-point substance is the slushy, icy layer that veneers a volumetric rocky mantle, which is surrounded by an atmosphere of mostly hydrogen and helium.

The scientists also observed that ice and gas giants like Uranus may be natural laboratories for learning about atmospheres. This absence of solid ground means that cloud formation, storm development, and connections between wind patterns are all part of a unified system— a kind of warm, wet, swirling ocean of air that we call the atmosphere.

This is according to postdoctoral researcher Emma Dahl of the California Institute of Technology. “We can find out why we have clouds, why we have storms, and why we have wind, not from the many thousands of objects that we have on the surface here on the Earth, but from the total atmosphere that we have over the mountain,” Dahl said in the NASA statement.

Over the next six years, Uranus will occult several dimmer stars, offering further chances to observe the process, according to NASA officials. But the next big event with a brighter star is expected in 2031, presenting yet another opportunity for astronomers to refine their ideas of this remote ice giant’s highly active atmosphere and delicate rings. 
 

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Super Earths are Quite Common Outside the Solar System, New Study Reveals

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April 26, 2025

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Super Earths are Quite Common Outside the Solar System, New Study Reveals

A team of international astronomers, led by Weicheng Zang from the Centre for Astrophysics | Harvard & Smithsonian (Cfa), had announced the discovery of a planet whose size is twice that of Earth, and orbits around its star at a distance farther out than Saturn. These findings reveal how planets differ from our existing solar system. The discovery was first published in the Journal Science on April 25, 2025. Scientists fetched this data from the Korea Microlensing Telescope Network (KMTNet), also known as the largest microlensing survey to date.

This Super Earth, called a planet due to its size being bigger than Earth but smaller than Neptune, is more significant as it is a large study where the masses of many planets have been measured relative to the stars that they orbit. As per physics.org, the team of researchers found fresh information about the number of planets that surround the Milky Way.

Study by KMTNet

According to the study conducted using Korean Microlensing data in which light from faraway objects is amplified through the use of an interfering body, called a planet. This technique is very effective for finding planets at a far distance, between Earth and Saturn’s orbit.

This study is considered to be large for its kind because there are about three times more planets, including planets that are eight times smaller than the previous planets found with the help of microlensing. Shude Mao, a professor, said that the current data gives a hint of how cold planets are formed. With the help of KMTNet data, we can know how these planets were formed and evolved. KMTNet has three telescopes in South Africa, Chile and Australia.

Understanding the Exoplanets

Such studies show that the other systems can have a small, medium and large variety of planets in Earth’s orbit. CFA-led research suggests that there can be more Super Earth Planets in other solar systems’ outer regions. Jennifer Yee says that there is a possibility that outside the Earth’s trajectory, other galaxies may have more such planets that are bigger than Earth’s size yet smaller than Neptune.

Findings and Implications

Youn Kii Jung, who operates KMTNet, says that in Jupiter-like orbits, the other planetary systems may not be similar to ours. Scientists will try to determine how many such planets exist. A study indicates that there are at least as many super-Earths as there are Neptune-sized planets in the universe.

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Magnetic Fields Could Significantly Influence Oscillations in Merging Neutron Stars, Study Finds

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April 26, 2025

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Magnetic Fields Could Significantly Influence Oscillations in Merging Neutron Stars, Study Finds

Magnetic fields may significantly complicate how scientists interpret gravitational wave signals from neutron star mergers, a new study has revealed. These collisions, where two super-dense stellar remnants merge, have long offered astrophysicists a way to probe matter under extreme pressure. The results from the University of Illinois Urbana-Champaign and the University of Valencia reveal that robust magnetic fields form more complex and lengthy patterns in gravitational waves, thereby making it harder to decipher the inner workings of neutron stars. Results could doom post-merger signal interpretation strategies and the equation of states of dense matter as scientists prepare to observe the next generation of gravitational wave observatories.

Magnetic Fields Found to Distort Frequency Signals in Neutron Star Mergers

As per the study published in Physical Review Letters, the researchers simulated general relativistic magnetohydrodynamics — how the strength and arrangement of magnetic fields affect the frequency signals from the remnants left behind after a merger. They went represent real-world conditions by applying two different equations of state (EoS) for neutron stars, different magnetic field configurations, and several mass combinations.

According to lead researcher Antonios Tsokaros, the magnetic field can cause frequency shifts that can misidentify scientists into misattributing them as indications of other physical phenomena like phase transitions or quark-hadron crossover.

The discoveries also imply that scientists need to be cautious about how they interpret signals from neutron-star mergers, lest they slip into assuming how they form. They found that strong magnetic fields can change the emitted signals’ typical oscillation frequency, shifting them from what they should be and from what was predicted by one or another of the competing equations of state at play within these ferocious events.

They also discovered that in the most straightforward type of galaxy mergers they considered in their simulations, the magnetic field became overly amplified so that a greater proportion of the remnants of the merger are more likely to produce further gravitational wave emissions.

Magnetic Fields Hold Key to Unlocking Secrets of Neutron Star Mergers

Neutron stars are what remains of massive stars that have collapsed, and they contain matter so dense that a full teaspoon would weigh billions of tonnes. They have thermodynamic properties that are determined by the EoS and magnetic fields, some orders of magnitude stronger than those that one can produce in a human laboratory.

These extreme features also make neutron stars useful for probing the laws of physics under intense pressure and magnetism. Ever since it was detected in both gravitational waves and gamma rays in 2017, the scientific community has been buzzing about research on neutron star mergers, leading to ever-growing numbers of studies related to these types of mergers.

Professor Milton Ruiz also warns that it would be a mistake to misinterpret observations in the future without considering the effects of the magnetic fields. Higher-resolution simulations are needed, the researchers said, to refine our understanding of how magnetic fields shape cosmic happenings, and endeavours like the Einstein Telescope and Cosmic Explorer loom on the horizon.

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