Aug 19th: See Comets & Weird Centaur

By on August 19, 2017 in

Podcaster: Dr. Al Grauer
Travelers in the Night Digest: 315 & 316 – See Comets & Weird Centaur

Organization: Travelers in The Night

Link : Travelers in the Night ; @Nmcanopus

Description: Today’s 2 topics:

  • 2017 may be a better than 2016 for comet viewing. Comet 41P Tuttle-Giacobini-Kresak put on a show last April. Catalina teammate Jess Johnson discovered Comet C2015 V2 Johnson. It was around in June but binoculars were needed to see it.
  • Richard Kowalski of Mt. Lemmon discovered 2016 WM48, a centaur. Part asteroid and part comet. In May it started to show cometary traits as was re-designated as a comet.

Bio: Dr. Al Grauer is currently an observing member of the Catalina Sky Survey Team at the University of Arizona.  This group has discovered nearly half of the Earth approaching objects known to exist. He received a PhD in Physics in 1971 and has been an observational Astronomer for 43 years. He retired as a University Professor after 39 years of interacting with students. He has conducted research projects using telescopes in Arizona, Chile, Australia, Hawaii, Louisiana, and Georgia with funding from NSF and NASA.

He is noted as Co-discoverer of comet P/2010 TO20 Linear-Grauer, Discoverer of comet C/2009 U5 Grauer and has asteroid 18871 Grauer named for him.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2017, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at

315 – See Comets
2017 is looking to be much better for comet enthusiasts than was 2016. Opportunities for viewing include seeing a comet with your unaided eye, getting an even better view with a pair of binoculars, and/or if you have access to a telescope with an electronic camera being part of an international effort which will study rapid cometary outbursts in brightness.

Comets are notoriously unpredictable and can rapidly change in brightness as they are warmed by the Sun .

Comet 41P/Tuttle-Giacobini-Kresak orbits the Sun every five and a half years, has a nucleus about a mile in diameter, is known to have brightness flares, and could reach naked eye brightness in the spring of 2017. At the end of April it will pass near the Globular Cluster M92 creating an interesting photographic opportunity.

Comet C/2015 V2 (Johnson) was discovered by my Catalina Sky Survey teammate Jess Johnson on 3 November 2015 when it was further from the Sun than the planet Jupiter. Since then it has been traveling on a hyperbolic path towards our neighborhood. It will good viewing for observers in the northern hemisphere from February until it reaches maximum brightness in May of 2017. It will be nearest the Sun in June of 2017 and after that it will continue on its path into interstellar space. Observers in the southern hemisphere will be able to view Jess’s comet until the end of 2017. Eons from now Comet C/2015 V2 Johnson may enter another solar system and treat any viewers who might be there to ghostly cometary appearance.

316 – Weird Centaur
My Catalina Sky Survey teammate Richard Kowalski was surprised to find a moving point of light on some his images which was more than 50 times brighter than a typical Earth approaching object he observes . He was even more amazed when it was not cataloged as a known object and he reported his observations to the Minor Planet Center. A couple of hours before Richard spotted it, scientists using the Space Surveillance Telescope in New Mexico had picked up this unknown object on some of their images but did not immediately report their observations. For the next 67 hours the new object was tracked by telescopes at 24 different observatories around the world. These observations allowed the Minor Planet Center to calculate an orbit, give it the name 2016 WM48, and classify it as a Centaur. Centaurs are named after the mythical beasts which were half human and half horse perhaps because they have characteristics of both asteroids and comets.

Richard’s object, 2016 WM48, is about a mile in diameter. We don’t know if it has rings, tiny moons, or a gas cloud surrounding it as some other Centaurs do. 2016 WM48 must have had a catastrophic collision in the past few million years which put it on a very elliptical path which is tipped at 60 degrees or so to the solar system’s plane. Centaurs do not have stable orbits. Their paths are changed as they come near to the giant planets Jupiter, Saturn, Uranus, and Neptune. A Centaur’s fate is to likely collide with the Sun or a planet or perhaps even be ejected from the solar system

End of podcast:

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About Al Grauer

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