This is the image of comet 46P/Wirtanen captured by NASA’s Hubble Space Telescope, when it was moving at a distant of 7.4 million miles from Earth on 13th December, 2018. But the comet is not visible clearly due to a cloud of gas and dust called coma. It is produced by the comet while traveling through the inner solar system owing to hot sunlight. The spacecraft’s Wide Field Camera 3 (WFC3) took this high-resolution image by applying blue color which helped create the composite image.
Generally, it is very difficult to study the inner section of a comet’s coma because of its long distance from Earth. But this flyby of the comet 46P/Wirtanen was so close to Earth and astronomers grabbed this opportunity to examine it in detail. To study the nucleus of the comet’s coma, they employed NASA’s Chandra X-ray Observatory, the Neil Gehrels Swift Observatory and Hubble Space Telescope. They tried to know the composition of the comet’s ices and how sunlight and solar radiation change its chemical properties.
This image of the glowing comet 46P/Wirtanen is taken by SOFIA, NASA’s Stratospheric Observatory for infrared Astronomy, while traveling at 40,000 feet above the ground.
The study of the comet’s water may figure out how water originated in the solar system. So SOFIA is trying to analyze different types of hydrogen available in the comet’s water. They are trying to match the chemical fingerprints of hydrogen in the comet’s water with the hydrogen presence in Earth’s water. SOFIA has already studied the comet’s water using infrared light which are being examined by scientists.
On 16th December, 2018, when the comet 46P/Wirtanen flied by Earth, the distance between them was only 7 million miles which was known as a closest approach by the comet. This close approach helped scientists run scientific experiment from Earth which is generally not possible. Though, 46P/Wirtanen is the brightest comet, it is very difficult to detect with open eyes even in a very dark sky. You need binoculars or a telescope to view it.
Source:
https://www.nasa.gov/feature/goddard/2018/nasa-telescopes-take-a-close-look-at-the-brightest-comet-of-2018