The Hubble Space Telescope has taken its closest images to date of the newest visitor to the night sky, C / 2020 F3 NEOWISE, after it has passed the sun. The new images were taken on August 8 and show the comet’s bright nucleus and its coma.
Comet NEOWISE is the brightest comet visible in the northern sky since the time of Hale-Bopp, which was visible in 1997. The object is currently traveling at about 60 kilometers per second, with its maximum approach to the Sun on July 3. For more than a month, the comet has been heading towards the outer regions of the solar system, from where it will return to the vicinity of the sun in…. 7,000 years.
The Hubble observations made it possible to take the first ever image of a comet of this brightness, at such a resolution, after passing through the perihelion of the orbit. Earlier attempts to photograph other bright comets (such as ATLAS) have always failed as comets decay near perihelion under the influence of intense sunlight.
Comet NEOWISE survived perihelion of its orbit
Comets often decay due to thermal and gravitational interactions during a close pass near the Sun. However, the Hubble image shows that the nucleus of the NEOWISE comet has survived in its entirety. Of course, the nucleus itself is too small for Hubble to observe directly. This ball of ice is no more than 4.8 km in diameter. Instead, the picture shows a large cloud of gas and dust surrounding the core. The diameter of this cloud is approximately 18,000 km.
The Hubble data also shows a pair of jets emitted from the nucleus in opposite directions. They are visible as cones of dust and gas attached to the comet’s nucleus. Further away from the nucleus, they curve into a wider fan, which is caused by the comet’s rotation. Jets are made of matter that was formed from ice that sublimated beneath the comet’s surface and was then ejected from it at high speed.
The Hubble images also revealed the color of the dust emitted from the comet and how it changes as it moves away from the Sun. This in turn may allow us to explain how solar radiation affects the content and structure of this dust and coma. The ultimate goal here is to establish the primary properties of the dust.
Photographing comets is not new to Hubble
The Hubble Space Telescope has photographed interesting comets before.
In April 2020, the collapse of the ATLAS comet was photographed.
In October and December 2019, Hubble photographed interstellar comet 2I Borisov.
The Hubble Space Telescope photographs the comet NEOWISE