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Ten months after launch, NASA’s asteroid-deflecting DART spacecraft neared a planned impact with its target on Monday in a test of the world’s first planetary defense system, designed to prevent a doomsday collision with Earth.

The cube-shaped “impactor” vehicle, roughly the size of a vending machine with two rectangular solar arrays, was on course to fly into the asteroid Dimorphos, about as large as a football stadium, and self-destruct around 7pm EDT (4:30 IST) some 6.8 million miles (11 million km) from Earth.

The mission’s finale will test the ability of a spacecraft to alter an asteroid’s trajectory with sheer kinetic force, plowing into the object at high speed to nudge it astray just enough to keep our planet out of harm’s way.

It marks the world’s first attempt to change the motion of an asteroid, or any celestial body.

DART, launched by a SpaceX rocket in November 2021, has made most of its voyage under the guidance of NASA’s flight directors, with control to be handed over to an autonomous on-board navigation system in the final hours of the journey.

Monday evening’s planned impact is to be monitored in real time from the mission operations center at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

DART’s celestial target is an asteroid “moonlet” about 560 feet (170 metres) in diameter that orbits a parent asteroid five times larger called Didymos as part of a binary pair with the same name, the Greek word for twin.

Neither object presents any actual threat to Earth, and NASA scientists said their DART test cannot create a new existential hazard by mistake.

Dimorphos and Didymos are both tiny compared with the cataclysmic Chicxulub asteroid that struck Earth some 66 million years ago, wiping out about three-quarters of the world’s plant and animal species including the dinosaurs.

Smaller asteroids are far more common and pose a greater theoretical concern in the near term, making the Didymos pair suitable test subjects for their size, according to NASA scientists and planetary defense experts.

Also, their relative proximity to Earth and dual-asteroid configuration make them ideal for the first proof-of-concept mission of DART, short for Double Asteroid Redirection Test.

Robotic mission suicide

The mission represents a rare instance in which a NASA spacecraft must ultimately crash to succeed.

The plan is for DART to fly directly into Dimorphos at 15,000 miles per hour (24,000 kph), bumping it hard enough to shift its orbital track closer to its larger companion asteroid.

Cameras on the impactor and on a briefcase-sized mini-spacecraft released from DART days in advance are designed to record the collision and send images back to Earth.

DART’s own camera is expected to return pictures at the rate of one image per second during its final approach, with those images streaming live on NASA TV starting an hour before impact, according to APL.

The DART team said it expects to shorten the orbital track of Dimorphos by 10 minutes but would consider at least 73 seconds a success, proving the exercise as a viable technique to deflect an asteroid on a collision course with Earth – if one were ever discovered. A small nudge to an asteroid millions of miles away could be sufficient to safely reroute it away from the planet.

The test’s outcome will not be known until a new round of ground-based telescope observations of the two asteroids in October. Earlier calculations of the starting location and orbital period of Dimorphos were confirmed during a six-day observation period in July.

DART is the latest of several NASA missions in recent years to explore and interact with asteroids, primordial rocky remnants from the solar system’s formation more than 4.5 billion years ago.

Last year, NASA launched a probe on a voyage to the Trojan asteroid clusters orbiting near Jupiter, while the grab-and-go spacecraft OSIRIS-REx is on its way back to Earth with a sample collected in October 2020 from the asteroid Bennu.

The Dimorphos moonlet is one of the smallest astronomical objects to receive a permanent name and is one of 27,500 known near-Earth asteroids of all sizes tracked by NASA. Although none are known to pose a foreseeable hazard to humankind, NASA estimates that many more asteroids remain undetected in the near-Earth vicinity.

NASA has put the entire cost of the DART project at $330 million (roughly Rs. 2,700 crore), well below that of many of the space agency’s most ambitious science missions.

© Thomson Reuters 2022

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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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