- nemesis maturity
Now we know why Comet NEOWISE (C/2020 F3) is so bright. Its nucleus is huge. Researchers working with NASA’s NEOWISE spacecraft have analyzed infrared emissions from the comet’s core in discovery images from March 2020. The glow is proportional to the size of the nucleus–the nugget of dust and frozen gas at the heart of the comet. “From its infrared signature, we can tell that the nucleus is about 5 kilometers across,” say researchers. 5 km is extremely large for a comet approaching this close to the sun (think Comet McNaught-sized), which explains its high activity. On July 3rd, Comet NEOWISE passed by the sun near the orbit of Mercury. The oversized nucleus helped it survive the encounter, which some comets would have found too hot to handle. Now NEOWISE’s sun-heated core is spewing massive amounts of dust and gas, creating a worldwide sensation. NASA’s Parker Solar Probe was at the right place at the right time to capture a unique view of comet NEOWISE on July 5, 2020.
Processed data from the WISPR instrument on NASA’s Parker Solar Probe shows greater detail in the twin tails of comet NEOWISE. The lower, broader tail is the comet’s dust tail, while the thinner, upper tail is the comet’s ion tail. For Comet NEOWISE, the future looks bright. Its large nucleus is a reservoir of dust and gas that should continue to fill the comet’s double tail with visible material for weeks to come. NEOWISE is now visible in the evening sky. At the moment “Evening Comet” NEOWISE is still a horizon-hugger, low and hard to see. However, it will climb higher in the sunset sky as July unfolds. After July 15th, sunset will be the time and place to see the comet as it rockets northward toward the Big Dipper.