Astronomers catch asteroid as it makes close flyby of Earth

Friday, February 3, 2017, 4:53 PM - A small asteroid flew past Earth on Thursday, and Slooh's telescope on the ground caught the tiny space rock as it whizzed by at less than half the distance to the Moon. Plus, spectacular closeup views of Saturn's rings from the Cassini probe. It's Science Pics of the Week!

Asteroid 2017 BS32 makes a close flyby

On Thursday, February 2, at around 3 p.m. EST - while many of us were still discussing the groundhogs' prognostications from earlier in the day - a small space rock, roughly the size of a school bus, went whizzing past Earth. There are plenty of asteroids out in near-Earth space, but this one was slightly more remarkable, because it was only just discovered, about three days beforehand, and it passed inside the Moon's orbit.

Credit: Minor Planet Center/S. Sutherland

At its closest, 2017 BS32 came within 150,000 kilometres of Earth, or about 40 per cent of the distance to the Moon's orbit. It did so at an angle that made it completely harmless to Earth, though, as the orbit plots above reveal.

While it made that close flyby, Slooh astronomer Paul Cox had one of the observatory's telescopes trained in its general location in space, and he managed to capture images of it! Watch below as Slooh host Gerard Monteux and Slooh astronomer Eric Edelman discuss the asteroid and reveal Paul's images of it.

And if it was difficult to see in the video, here are close-up images taken by Paul Cox, showing the streak the asteroid left in the long-exposure pictures he took.

This was the second newly-found asteroid in as many weeks that was discovered just before it passed between Earth and the Moon. Asteroid 2017 BX was first spotted on January 20, by the Pan-STARRS 1 telescope, in Hawaii's Haleakalā National Park, before it swept past Earth at around 70 per cent the distance of to the Moon.

The small size of these asteroids shows just how good our survey systems are getting at spotting near-Earth asteroids.

Saturn's rings just keep getting better!

What we've seen of Saturn's rings so far has been pretty amazing, but NASA's Cassini spacecraft just keeps sending back more images that keep raising the bar on exactly what "amazing" means.

Take its latest offerings, for example:

Clumps of "straw" in Saturn's outer B ring, caused by a 2-to-1 resonance of the ring particles to the icy moon, Mimas. This image has been processed to remove blemishes due to dust and cosmic ray particles. Click or tap the image to see the original. Credit: NASA/JPL-Caltech/Space Science Institute

The bright streaks in the outermost part of the ring, in the view above, are called "straw" by mission scientists. As Saturn's rings and moons orbit the planet, the particles in this region of the B ring travel around the planet exactly twice for every time the moon, Mimas, makes one orbit. This causes Mimas' gravity to tug on these particles at such regular intervals that it causes these disturbances.

Also, these close-up views of the planet's rings have revealed a multitude of what are known as "ring propellers" - small, propeller-shaped disturbances in the ring structure, caused by the gravitational pull of tiny moonlets - to small to see, even in these images - that are embedded in the ring.

Drag the slider back and forth across the image to reveal the location of these ring propellers.

In this different view of the rings, Cassini captures a lone propeller against the backdrop of shadowy rings, giving us a much better look at one.

A ring propeller advances along its orbit around Saturn in this animation, from three different images taken on Jan 9, 2017. Credit: NASA/JPL-Caltech/Space Science Institute

These propellers are produced by the gravity of these moonlets in much the same way as we recently saw the moon Daphnis causing ripples in the edges of the Keeler Gap.

Sources: Slooh Community Observatory | NASA | NASA