The Hubble Space Telescope was used to observe comet NEOWISE, formally C/2020 F3, which notably shows the coma surrounding its nucleus. The images released were captured on August 8, and are the first photos taken by Hubble of such a bright comet at such a high resolution after it passed close to the Sun. On July 3, NEOWISE passed approximately 43 million kilometers from the Sun, the most critical moment because sometimes comets are torn to pieces. The new images show that this time the comet survived in its entirety and will return to the inner solar system only in 7,000 years.
Comet C/2020 F3 was also called NEOWISE because it was discovered on March 27, 2020, during the mission of the same name, which stands for Near-Earth Object Wide-field Infrared Survey Explorer, in which NASA’s WISE space telescope was repurposed to discover the so-called NEOs (Near-Earth Objects) and trace the orbits of the already known ones. It usually discovers new asteroids, which can be potentially dangerous if they cross the Earth’s orbit, but sometimes it spots comets. C/2020 F3 is a long-period comet, the type that can take many thousands of years to complete an orbit.
During July, comet NEOWISE was also visible to the naked eye, and is considered the brightest comet visible from the Northern Hemisphere since 1997, when the Hale-Bopp passed through the inner solar system. During these passages, the solar emissions are intense enough to sublimate the ice, especially of water but also of other volatile compounds such as carbon dioxide, forming the coma around the nucleus and the tail. In the case of NEOWISE, the nucleus has an estimated length of less than 5 kilometers, but in recent weeks the cloud of gas and dust around it was in its period of maximum extension, and in the image captured by the Hubble Space Telescope it’s around 18,000 kilometers across.
The Hubble Space Telescope made it possible to capture various details of the NEOWISE comet that offer information about its activity and composition. Two jets from the nucleus are visible extending in opposite directions. They’re cones of gas and dust that are emitted following the sublimation of the ice, which also bring with them other materials present on the comet. The analysis of the photos can reveal the colors of the materials that are emitted and their changes, which depend on their composition. This helps to understand how the comet’s activity changes over time, in this case as it’s moving away from the Sun.
Comets are considered to be a kind of fossil containing materials that have changed little or nothing since their formation. This means that their study offers insights into the conditions that existed in the early solar system. Comets brought water to the planets and possibly organic compounds as well. These are all reasons why interest in comets has increased in recent decades. Now NEOWISE is at the center of attention, there will be many more in the future.
