Canadians will get a nice view of a waning crescent moon this weekend, but new mini-moon will remain stubbornly hard to spot
This Sunday at 3:54 p.m. Eastern Time, Canadians under clear skies will be able to watch a thin sliver of the moon as it heads toward the western horizon, setting at just after 6 p.m.
Did I say THE moon? I meant A moon. Because the afternoon of Sept. 29 is also when Earth will briefly pick up a second moon, much smaller than our well known satellite; a so-called mini-moon or moonlet.
The itsy bitsy companion, with the unprepossessing name of asteroid 2024 PT5, won’t be visible to the naked eye. That’s because it’s only about 10 metres in size, roughly as big as a house, compared to the moon’s 3,500-kilometre diameter, which makes it the size of — well, the moon. It will also be almost 10 times further from the Earth than our regular moon, which also means there’s no chance of it hitting us.
But it will be a satellite of the Earth, or at least until Nov. 25, when it will slip out of our planet’s gravitational grasp and wander back into the small asteroid belt whence it came. In other words, by the time big moon goes through two cycles, little moon will have left.
As its name suggests, 2024 PT5 was discovered just this year by the Asteroid Terrestrial-impact Last Alert System (ATLAS), a robotic survey mission funded by NASA and tasked with detecting small near-Earth objects before they collide with our planet — or, in this case, go into brief orbit around it.
Before that the most recent moonlet known to have been captured even into temporary orbit by Earth’s gravity was 2006 RH120, a similar-sized asteroid that was in orbit for a few months ending in June 2007.