Teaching
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- Dr. Paul Wiegert
- Physics and Astronomy 238
- Phone:(519) 661-2111 x 81327
- email:pwiegert {at} uwo.ca
Could particles be reaching us from alpha Centauri?(7-Feb-2025) Alpha Centauri is a triple star system only 4.3 light years from us. If it is ejecting material at a rate comparable to our own Solar System --where Jupiter occasionally gravitationally "slingshots" asteroids and comets out into interstellar space-- some of that material could be currently around us, though probably not in any great numbers. An analysis of what to expect of asteroids and meteoroids arriving from alpha Centauri was published in the Planetary Science Journal by Gregg & Wiegert (2025) and is available at this link. Click the animation to the left or here for related animations. |
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Could a small asteroid impact deflect Apophis?(15-Aug-2024) 99942 Apophis is an asteroid confidently expected to pass our planet at a distance of tens of thousands of kilometers in 2029. But calculations to date have not yet considered the effect of a possible small asteroid impact on Apophis, an impact of the type which is frequently observed on Earth as a meteor or fireball. The risk of such an event is small: only a 1 in a million chance that Apophis could be deflected significantly, and only 1 in a billion that such a deflection could put the Earth in immediate danger. The analysis appears in the peer-reviewed Planetary Science Journal. Click here for more information, including a link to the paper. Click the animation to the left for a larger version on YouTube. |
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Asteroid encounters with 99942 Apophis(4-Mar-2024) Asteroid 99942 Apophis is a 340 meter diameter object on course to miss our planet by a safe margin in 2029. However, that could change in the highly unlikely case that Apophis collides with another asteroid in the mean time. This risk is extremely small but to quantify it, we identified close encounters between known asteroids and Apophis. We show that the 1300 meter (0.8 mile) diameter asteroid 4544 Xanthus will miss Apophis by 500,000 km in December 2026. Their Minimum Orbit Intersection Distance (MOID) is less than 10,000 km, with Xanthus passing that point just four hours after Apophis. We also identified other asteroid encounters of interest in a peer-reviewed report accepted by the Planetary Science Journal. Click here for more information, including a link to our paper. Click the animation to the left for a larger version on YouTube. |
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How the first quasi-moon got its name..."Zoozve"(26-Jan-2024) Ok, this is only partly my research but too interesting not have here. Check out Radiolab's podcast about asteroid 2002 VE68, the first known "quasi-moon" and how an improbable chain of events lead to its being named "Zoozve". Click on the left or here for a larger view of the animation on Youtube, which shows Zoozve's path within our Solar System. Check out my own "its-so-old-its-almost-retro" page on quasi-satellites (quasi-moons and quasi-satellites are the same thing). |
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An unexpected visitor from the outer limits(12-Dec-2022) In our Solar System, icy material is thought to originate far from the Sun, where it's cold. Rocky ice-free material should come from the regions much closer to the Sun. However, a rocky meteoroid observed over Alberta Canada in 2021 arrived from our planetary system's outermost edge. The significance of this unusual rock from the icy Oort Cloud is discussed in Vida et al. (2022) published in the December 12 2022 issue of Nature Astronomy. Click the animation to the left for a larger version on YouTube, or check out our paper at Nature Astronomy. |
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Asteroid 2022 WJ1 impacts Canada(19-Nov-2022) Asteroid 2022 WJ1 was first spotted by the Catalina Sky Survey in Arizona, when the approaching one-meter diameter asteroid was only hours from striking Earth. Once it struck the top of our atmosphere, the asteroid became a fireball, flashing across the skies of Southern Ontario at 3:26 am local time. Residents along the Lake Ontario shoreline from Grimsby to Niagara-on-the-Lake Ontario should check their yards and driveways for new black rocks, which could be meteorites. Check out the press release or click on the video to the left for a youtube video. |
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Earth's second Trojan asteroid 2020 XL5(10-Nov-2021) A 'Trojan' asteroid is one that shares the orbit of a planet as they both travel around the Sun. The second Trojan asteroid for the Earth was reported in Hui et al (2021), accepted for publication in the Astrophysical Journal Letters. The animation to the left shows this asteroid, along with the first Trojan asteroid 2010 TK7 and the first known Earth co-orbital asteroid (a more exotic variation on the Trojan orbit) 3753 Cruithne, shown in a frame which rotates along with our planet. Click the animation for a larger version on YouTube, or here for the HD .mp4 (60 Mb) or a smaller half-HD .mp4 (26 Mb). |
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Grad student first to spot near-Earth asteroid(23-Nov-2020) While using a remote-controlled telescope located on a mountain top in Spain, Western University graduate student Cole Gregg noticed a bright dot moving rapidly across his field of view. The object turned out to be a small asteroid, estimated at 50 to 100 meters in diameter, which was passing through near-Earth space. He spotted the asteroid –which now has the temporary designation ALA2xH– in the constellation of Cetus on Nov 18. Having passed harmlessly 30,000 km over all our heads, the asteroid is now headed safely back out into space. See the discovery images, a a larger version of the flyby simulation or the press release (static version here). |
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Exomoon candidates from the Kepler spacecraft(24-Jun-2020) There is a range of parameter space where the Kepler Space Telescope is sensitive to the transit timing variations (TTVs) exomoons might produce in their parent planet, though the moons themselves would be too small to detect via their own transits. Eight systems from the Kepler data show TTVs could be plausibly explained by an unseen exomoon. Click on the animation at the left for more information. |
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Other and older researchDetecting planets around other stars; telescopic searches for asteroids and comets; modelling the hazard to spacecraft from meteors; asteroids temporarily captured as Earth satellites. Click on the left to find out more... |
