October 11, 2022

James Webb Telescope gathered data observing Phaethon today. Driss Takir, a planetary scientist with NASA's Astromaterials Research and Exploration Sciences division at Johnson Space Center in Houston, described Phaethon as an "active asteroid with a comet-like tail formed by the ejection of dust particles occurring when the asteroid is moving closer to the Sun." Every year, when Phaethon's dusty path crosses Earth's orbit, the resulting particles ignite in our atmosphere and produce the magnificent Geminid meteor shower, which we view around the middle of December. 

Phaethon, which passes by Earth once a year at a distance of about 6 million miles, is a reasonably close-by - and potentially dangerous - object that scientists prefer to keep a watch on. Phaethon resembles a typical asteroid in many ways: it is rocky, big (measuring 3 miles across), contains carbon, and is thought to be an early solar system leftover from when it originated some 4.5 billion years ago. Phaethon travels through our solar system on a more comet-like trajectory, though. Although there are asteroids in other parts of the solar system, including those that pass close to Earth, the majority of asteroids in our solar system orbit the Sun between Mars and Jupiter. However, by making a near trip around the Sun and heating it to 1,500 degrees Fahrenheit, Phaethon more closely resembles a comet. Phaethon not only orbits like a comet but also has a comet-like appearance, with a dust tail of debris following behind it as it approaches the Sun. A portion of the ice and dust that make up comets vaporizes as they travel through space, creating their tails. Knowing this, scientists have long pondered whether Phaethon's tail is also brought on by melting ice and the release of water-rich minerals. 

With James Webb Telescope observing this asteroid, scientists will be able to learn more about the unique characteristics of this asteroid which makes it behave like a comet in many ways.

Credit: NASA