1973 Comet Kohoutek, first sighted #OTD by Czech astronomer Luboš Kohoutek. http://j.mp/1OXLs9O http://pic.twitter.com/ZFDtRinIV7

— On This Day in Math (@OnThisDayinMath) March 7, 2016

from http://twitter.com/OnThisDayinMath
on: March 07, 2016 at 03:00PM

In 1982, Halley's Comet was observed on its 30th recorded visit to Earth, http://j.mp/1PlX4sM http://pic.twitter.com/Avo8tuv0yK

— On This Day in Math (@OnThisDayinMath) October 16, 2015

from http://twitter.com/OnThisDayinMath
on: October 16, 2015 at 09:00AM

1750 Caroline Lucretia Herschel born, first professional woman astronomer? Comet finder. http://t.co/0j3Ms2SsZu

— On This Day in Math (@OnThisDayinMath) March 16, 2014

from http://twitter.com/OnThisDayinMath
on: March 16, 2014 at 11:54AM