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Ephemeris: 07/08/2025 – A third interstellar visitor discovered
This is Bob Moler with Ephemeris for Tuesday, July 8th. Today the Sun will be up for 15 hours and 23 minutes, setting at 9:29, and it will rise tomorrow at 6:06. The Moon, 2 days before full, will set at 4:20 tomorrow morning.
One week ago the third interstellar interloper to the solar system was discovered. It’s known as 3I/ATLAS. The “I” means interstellar. That is, it came from another star system. It is heading in now, crossing the asteroid belt. It will reach its closest to the Sun on October 29th, at about the distance of Mars, which it will get very close to by the way, and head out into interstellar space. This is an incredibly fast object, far exceeding the escape velocity of the Sun, and its path is only deflected by 17° by its encounter by the Sun’s gravitational force. Due to it high speed, it was first thought to be a Near Earth Object. Pre-discovery photographs showed that it was much more distant. With the new Rubin Observatory coming online we’ll discover many more.
The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.
Addendum
09/17/2019 – Ephemeris – It looks like another interstellar object has been found passing through the solar system
Ephemeris for Tuesday, September 17th. Today the Sun will be up for 12 hours and 26 minutes, setting at 7:50, and it will rise tomorrow at 7:24. The Moon, 3 days past full, will rise at 9:45 this evening.
Last week Monday I talked about a project to detect interstellar meteoroids that hit the Moon. It turns out we don’t have to wait that long. This past August 30th, Gennady Borisov of the Crimean Astrophysical Observatory discovered apparent comet since designated C/2019 Q4 (Borisov). It will approach the Sun just outside Mars orbit in December. It’s moving at over 25 miles per second (41 km/s) or nearly 92 thousand miles an hour (150,000 km/hr). In 2017 the first interstellar body discovered to enter our solar system was spotted, ‘Oumuamua. It was already past its closest to the Sun when found. This one is still approaching and visibly out gassing, so we’ll find out much more of its composition.
Addendum
Color photograph of C/2019 Q4. Image Credit: Gemini Observatory/NSF/AURA
Orbit of C/2019 Q4 (Borisov). Credit: NASA/JPL-Caltech
Check out these links:
https://www.syfy.com/syfywire/wait-another-interstellar-object-is-passing-through-the-solar-system
Bob Moler's Ephemeris Blog 