NASA’s Hubble Space Telescope has determined the size of the largest icy comet nucleus
ever found.
And, it’s big!
With a diameter of approximately 80 miles across, it’s about 50 times larger than
typical comets.
Its 500-trillion-ton mass is a hundred thousand times greater than the average comet.
The challenge was distinguishing the solid nucleus from the huge dusty coma enveloping
it.
The comet is so far away that its nucleus is too small for Hubble to resolve.
Instead, Hubble found a bright spike of light at the nucleus’ location.
Astronomers made a computer model of the surrounding coma and adjusted it to fit the Hubble images.
Then, the glow of the coma was subtracted leaving behind the starlike nucleus, size
was then estimated from it’s brightness.
The behemoth comet is barreling this way at 22,000 miles per hour.
But don’t worry.
It won’t get any closer than roughly 1 billion miles away from the Sun, slightly farther
out than Saturn.