Researchers from Finland, Canada, and Russia have discovered an unusual, hourglass-shaped dust trail of the comet 17P/Holmes. The particles that formed the dust trail were released by the most powerful of the thus-far documented outbursts by a comet. It happened in October 2007. Astronomers carried out observations of the cometary dust trail using telescopes in Australia, Finland, and the U.S. The first stage of observations lasted from 2013 to 2015, and the second one was from 2020 to 2021. The description of this research is published in Monthly Notices of the Royal Astronomical Society.
