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Astronomers have detected in the stellar halo that represents the Milky Way’s outer limits a group of stars more distant from Earth than any known within our own galaxy — almost halfway to a neighboring galaxy.

The researchers said these 208 stars inhabit the most remote reaches of the Milky Way‘s halo, a spherical stellar cloud dominated by the mysterious invisible substance called dark matter that makes itself known only through its gravitational influence. The furthest of them is 1.08 million light years from Earth. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

These stars, spotted using the Canada-France-Hawaii Telescope on Hawaii’s Mauna Kea mountain, are part of a category of stars called RR Lyrae that are relatively low mass and typically have low abundances of elements heavier than hydrogen and helium. The most distant one appears to have a mass about 70 percent that of our sun. No other Milky Way stars have been confidently measured farther away than these.

The stars that populate the outskirts of the galactic halo can be viewed as stellar orphans, probably originating in smaller galaxies that later collided with the larger Milky Way.

“Our interpretation about the origin of these distant stars is that they are most likely born in the halos of dwarf galaxies and star clusters which were later merged – or more straightforwardly, cannibalised — by the Milky Way,” said Yuting Feng, an astronomy doctoral student at the University of California, Santa Cruz, who led the study, presented this week at an American Astronomical Society meeting in Seattle.

“Their host galaxies have been gravitationally shredded and digested, but these stars are left at that large distance as debris of the merger event,” Feng added.

The Milky Way has grown over time through such calamities.

“The larger galaxy grows by eating smaller galaxies — by eating its own kind,” said study co-author Raja GuhaThakurta, UC Santa Cruz’s chair of astronomy and astrophysics.

Containing an inner and outer layer, the Milky Way’s halo is vastly larger than the galaxy’s main disk and central bulge that are teeming with stars. The galaxy, with a supermassive black hole at its center about 26,000 light years from Earth, contains perhaps 100 billion–400 billion stars including our sun, which resides in one of the four primary spiral arms that make up the Milky Way’s disk. The halo contains about 5 percent of the galaxy’s stars.

Dark matter, which dominates the halo, makes up most of the universe’s mass and is thought to be responsible for its basic structure, with its gravity influencing visible matter to come together and form stars and galaxies.

The halo’s remote outer edge is a poorly understood region of the galaxy. These newly identified stars are almost half the distance to the Milky Way’s neighboring Andromeda galaxy.

“We can see that the suburbs of the Andromeda halo and the Milky Way halo are really extended – and are almost ‘back-to-back,'” Feng said.

The search for life beyond the Earth focuses on rocky planets akin to Earth orbiting in what is called the “habitable zone” around stars. More than 5,000 planets beyond our solar system, called exoplanets, already have been discovered.

“We don’t know for sure, but each of these outer halo stars should be about as likely to have planets orbiting them as the sun and other sun-like stars in the Milky Way,” GuhaThakurta said.

© Thomson Reuters 2023

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NASA’s Perseverance Rover Observes Googly Eye Eclipse on Mars

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November 1, 2024

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NASA's Perseverance Rover Observes Googly Eye Eclipse on Mars

NASA’s Perseverance rover which is positioned in the Jezero Crater on Mars, recently observed a remarkable celestial event as the moon Phobos drifted across the Sun. Captured on September 30, this moment offered a rare glimpse into Mars’ sky, where the unique “googly eye” effect of the eclipse unfolded for the rover’s Mastcam-Z camera. The video, released by NASA, illustrates the interplay of Martian moon orbits and provides valuable information on Phobos’ trajectory and its gradual shift towards Mars.

Unexpected Eclipse Creates ‘Googly Eye’ View on Mars

Perseverance, which has been observing Mars’ surface and sky since 2021, recorded the silhouette of Phobos moving rapidly across the Sun’s face from Mars’ western Jezero Crater. Phobos, the larger of Mars’ two moons, created a distinct “googly eye” visual effect as it partially blocked sunlight, a phenomenon not typically visible from Earth. The eclipse, captured on the mission’s 1,285th sol (Martian day), highlights Phobos’ swift orbit, which takes just 7.6 hours to complete a full circle around Mars. Due to its close orbit, Phobos regularly crosses Mars’ sky, allowing for these brief transits which last only about 30 seconds each.

Phobos’ Eerie Path and Future on Mars

Phobos, named by astronomer Asaph Hall in 1877 after the Greek deity associated with fear, measures about 27 kilometres at its widest. Unlike Earth’s larger moon, Phobos appears far smaller in the Martian sky. Its orbit brings it closer to Mars with time, which scientists predict will eventually cause Phobos to collide with the Martian surface within the next 50 million years. Past eclipses of Phobos, also recorded by other Mars rovers like Curiosity and Opportunity, continue to contribute essential data for understanding Mars’ moons and their shifting orbits.

Perseverance’s Mission and Future Mars Exploration

As part of NASA’s Mars 2020 mission, Perseverance focuses on exploring Martian geology and astrobiology. The mission, managed by NASA’s Jet Propulsion Laboratory (JPL), is the first to collect samples of Mars’ surface material, which are intended to be retrieved in future joint missions with the European Space Agency (ESA). Perseverance’s Mastcam-Z, developed with support from Arizona State University, Malin Space Science Systems, and the Niels Bohr Institute, plays a crucial role in gathering high-resolution imagery to support geological studies. This mission aligns with NASA’s broader objective of preparing for human exploration on Mars, beginning with the Artemis missions to the Moon.

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South Korea teams up with NASA to send solar research tool to ISS

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November 1, 2024

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South Korea teams up with NASA to send solar research tool to ISS

South Korea’s space agency announced plans on Friday to launch a solar coronagraph to the International Space Station (ISS) in a collaborative mission with NASA. Developed as part of the Coronal Diagnostic Experiment (CODEX), this instrument is set to observe and gather data on the Sun’s corona and the solar wind as well as the stream of charged particles that flows from the Sun’s outer atmosphere. The CODEX device is scheduled to be launched aboard SpaceX’s Falcon 9 from Florida’s Kennedy Space Center on Monday, as reported by Yonhap News Agency.

Bilateral Project to Examine Solar Atmosphere

The CODEX project represents a very important collaboration between the Korea Aerospace Research Institute (KASA) and NASA, with CODEX marking a pioneering achievement as the world’s first coronagraph equipped to measure temperature, velocity, and density within the solar wind. Once aboard the ISS, CODEX will be mounted on the station’s express logistics carrier, allowing for approx 55 minutes of solar observation in each 90-minute orbit around Earth. This data is expected to enhance researchers’ understanding of the solar wind, potentially aiding in space weather forecasting efforts.

South Korea’s Expanded Cooperation with NASA

Alongside the CODEX project, South Korea and the United States have broadened their partnership in space exploration. KASA and NASA signed a statement of cooperation, focusing on research initiatives including the Artemis lunar exploration programme. KASA’s involvement with the Artemis project includes studies on sustainable lunar exploration and advancements in Mars mission preparations. With this agreement, South Korea has become the fifth nation to officially collaborate with NASA on such initiatives.

Pioneering Studies and Technological Advancements

Under the framework of this agreement, South Korea and the US will work together on a variety of feasibility studies related to lunar landers, as well as advancements in communication, navigation, and astronaut support systems. In addition, collaborative efforts will span lunar surface science, autonomous power, robotic systems, and cis-lunar space operations—the area between Earth and the Moon.

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NASA’s satellite reveals fascinating tsunami data in Greenland

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November 1, 2024

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NASA's satellite reveals fascinating tsunami data in Greenland

An unprecedented nine-day tsunami following a significant rockslide in Greenland’s Dickson Fjord was recently recorded by the international Surface Water and Ocean Topography (SWOT) satellite, a collaborative mission by NASA and France’s Centre National d’Études Spatiales (CNES). The event, which took place in September 2023, saw a unique pattern of seismic waves resonate around the world, marking one of the rare instances where satellite data captured a prolonged natural phenomenon with such clarity.

Satellite’s Breakthrough Detection in Remote Fjord

As per a report by NASA, the rockslide unleashed over 25 million cubic meters of rock and ice into the fjord, displacing the water and creating a massive wave that moved rhythmically between the fjord walls every 90 seconds for nine consecutive days. NASA’s Jet Propulsion Laboratory scientist Josh Willis highlighted this as a first, saying, “SWOT’s technology allowed us to see the wave contours, something we couldn’t achieve before.” The water levels on the northern side of Dickson Fjord rose as high as 1.2 metres in contrast to the southern side, emphasising the powerful impact of the rockslide.

Advanced Technology for Global Hazard Monitoring

At an altitude of around 900 kilometres, SWOT utilises a Ka-band Radar Interferometer (KaRIn) to measure surface water height with precision. This technology captured the event’s effects in the confined fjord setting, which conventional altimeters could not do due to their larger footprint. Nadya Vinogradova Shiffer, a scientist at NASA Headquarters, noted that this capability highlights SWOT’s potential for monitoring hazards, contributing to preparedness and disaster risk reduction.

Innovative Partnership in Satellite Research

Since its launch in December 2022, SWOT has been instrumental in mapping global water levels. Developed with contributions from the Canadian and UK space agencies, NASA leads the mission’s U.S. operations, including the KaRIn instrument, with CNES managing various onboard systems and support. The data collected promises ongoing contributions to scientific understanding of Earth’s water dynamics.

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