Category: Space & Astronomy

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Astronomers may have spotted a planet in another galaxy for the first time

The hunt for exoplanets is venturing beyond the Milky Way. Astronomers using NASA's Chandra X-ray Observatory have detected what might be the first signs of a planet in another galaxy. The team noticed dips in X-ray brightness that hint at a planet transiting in front of a star in the Messier 51 (aka M51) galaxy 28 million light-years away. For context, all the exoplanet candidates in the Milky Way are no more than 3,000 light-years from Earth — this planet would easily set a distance record if confirmed.

The very nature of stars made the feat possible. As the researchers had to focus on X-ray bright binary systems where the region of bright rays is relatively tiny, the transit was considerably easier to spot. Conventional detection of nearby stars requires much more sensitive light detection, as a planet might only block a small amount of light from a given star.

The planet itself is believed to be as large as Saturn, but would orbit its hosts (a star 20 times the mass of the Sun as well as a black hole or neutron star) at twice the distance.

Scientists didn't believe the dimming was due to gas clouds or dust, as those aren't consistent with the event they recorded in M51. A planet, however, would line up with the data.

The challenge, as you might guess, is verifying that data. The planet's large orbit could rule out another transit for roughly 70 years, and it wouldn't be clear exactly when astronomers would have to take a look. The three-hour transit of this planet candidate didn't provide a large window. That's also assuming the 'living' star doesn't explode and bathe the planet in radiation.

If there's ever a confirmation, though, the discovery would be very significant. While there aren't many doubts that planets exist in other galaxies, it would be useful to have evidence of their existence. This could also significantly widen the scope of future planetary searches to include the galactic neighborhood, not just close-by stars.

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People first drove on the Moon 50 years ago today

NASA just celebrated another major moment in the history of Moon exploration. The New York Timesnoted that July 31st, 2021 marks the 50th anniversary of the Lunar Roving Vehicle's first outing — and the first time people drove on the Moon. Apollo 15 astronauts Dave Scott and Jim Irwin took the car on a stint to collect samples and explore the lunar surface more effectively than they could on foot.

Scott and Irwin would eventually drive the rover two more times (for a total of three hours) before returning to Earth. The Apollo 16 and 17 missions each had an LRV of their own. There was also a fourth rover, but it was used for spare parts after the cancellation of Apollo 18 and further missions. All three serving models remained on the Moon.

Early development was problematic, in no small part due to the lack of real-world testing conditions. They couldn't exactly conduct a real-world test drive, after all. The team eventually settled on a collapsible design with steel mesh wheels that could safely handle the Moon's low gravity, lack of atmosphere, extreme temperatures and soft soil.

The LRV was modest, with a 57-mile range, four 0.19kW motors and an official top speed of 8MPH. It was also expensive, with cost overruns bringing the price of four rovers to $38 million (about $249 million in 2021 dollars). It was key to improved scientific exploration during the later stages of the Apollo program, though, and it was also an early example of a practical electric vehicle — humans were using a battery-powered ride on the Moon decades before the technology became mainstream on Earth.

We wouldn't count on humans driving on the Moon any time soon, although that reflects the progress made in the 50 years since. NASA and other space agencies are now focused on robotic rovers that can explore the Moon without worries about crew safety. Those humans that do go on rides will likely use autonomous vehicles. Think of this anniversary as celebrating a first step toward the technology you see today.

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