A unique telescope that focuses light with a slowly spinning bowl of liquid mercury instead of a solid mirror has opened its eye to the skies above India. Such telescopes have been built before, but the 4-meter-wide International Liquid Mirror Telescope (ILMT) is the first large one to be purpose-built for astronomy, at the kind of high-altitude site observers prize—the 2450-meter Devasthal Observatory in the Himalayas.

Although astronomers must satisfy themselves with only looking straight up, the $2 million instrument, built by a consortium from Belgium, Canada, and India, is much cheaper than telescopes with glass mirrors. A stone’s throw from ILMT is the 3.6-meter, steerable Devasthal Optical Telescope (DOT)—built by the same Belgian company at the same time—but for $18 million. “Simple things are often the best,” says Project Director Jean Surdej of the University of Liège. Some astronomers say liquid mirrors are the perfect technology for a giant telescope on the Moon that could see back to the time of the universe’s very first stars.

When a bowl of reflective liquid mercury is rotated, the combination of gravity and centrifugal force pushes the liquid into a perfect parabolic shape, exactly like a conventional telescope mirror—but without the expense of casting a glass mirror blank, grinding its surface into a parabola, and coating it with reflective aluminum.

ESA’s Comet Interceptor mission to visit a pristine comet or other interstellar object just starting its journey into the inner solar system has been “adopted” this week; the study phase is complete and, following selection of the spacecraft prime contractor, work will soon begin to build the mission.

Comet Interceptor will share a ride into space with ESA’s Ariel exoplanet mission in 2029. The mission will build upon the successes of Rosetta and Giotto, ESA missions that both visited “short-period” comets. Though these missions completely transformed our understanding of comets, their targets had already swung around the sun many times and had therefore changed significantly since their creation.

Comet Interceptor aims to scrutinize a comet that has spent little time in the inner solar system, or is possibly visiting it for the first time. Whilst Rosetta’s target hailed from the rocky Kuiper Belt just beyond Neptune, Comet Interceptor’s could originate from the vast Oort Cloud, more than a thousand times further from the sun.

The distant star AU Microscopii may have mysterious cold spots. It seems to contain pockets of hydrogen that are more than 1500°C cooler than the surrounding areas, and astronomers aren’t sure why.

The James Webb Space Telescope dima_zel/ iStock

Between May 23 and 25, the James Webb Space Telescope (JWST) was hit by a micrometeoroid that has impacted one of its primary mirror segments, NASA said in a recent update on its website. The telescope continues to function at levels exceeding mission requirements.

A meteoroid is a fragment of an asteroid and can be either large or small. A micrometeoroid, though, is a microscopic fragment of a meteoroid and is smaller than a grain of sand. NASA estimates that millions of meteoroids and micrometeoroids strike the Earth’s atmosphere every day but most burn up due to the friction.

#PlanetExplorers brings you epic stories of exploration and discovery around five bodies in our solar system, told by the scientists who love and study them.