Archive for May 18, 2020

05/18/2020 – Ephemeris – Comets are fragile, especially this month’s crop

May 18, 2020 Comments off

This is Ephemeris for Monday, May 18th. Today the Sun will be up for 14 hours and 57 minutes, setting at 9:08, and it will rise tomorrow at 6:09. The Moon, half way from last quarter to new, will rise at 5:04 tomorrow morning.

Last month most of us astronomers were looking forward to seeing at least two naked-eye comets this month, with another just below naked-eye visibility. Our hopes have been dashed with the first two, Comet ATLAS is disintegrating and Comet SWAN has stopped brightening, and at its brightest, which would be barely visible in a dark sky, would be invisible in bright twilight, where it will be located. Comets are unpredictable. Each is their own beast. They are small bodies of ices dust and bits of rock. When they come inside the orbit of Jupiter the Sun’s heat sublimates their frozen gasses which shoot out along with dust and build a huge tenuous head called a coma that can be larger than Jupiter and a tail that extends millions of miles (kilometers).

The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Comet ATLAS disintegrates

Comet ATLAS disintegrates as witnessed by the Hubble Space Telescope. Currently there are 5 nuclear fragments being separately tracked. The color here is most not likely the true visual color. Click on the image to enlarge. Credit: NASA/ESA Hubble Space Telescope.