lizzyq

All I could think of was this:

SultanOfSwing

Any of our Canadian posters seen Steve yet?

Meet Steve, the curious ribbon of purplish light discovered in Alberta skies - Calgary - CBC News

steveq

Sold this to a place in New York, or at least got commission on it.

Steve

SultanOfSwing

Nice. Wouldn't mind one of those myself

Pulaski

So Florence is passing by tonight. She is a relatively large asteroid, 2.7 miles across, passing 4.4 million miles from Earth, and the largest object to come that close since NASA started tracking near the Earth asteroids.

If you don't have access to a telescope there is a virtual telescope that will apparently be providing coverage.

Bahtatboy

That was a dead link for me, but could be my firewall/vpn.

What'll it look like? Glowing, tail, sparks (no, probably not sparks)? Or just a pale glow (albedo 0.??)?

steveq

The units of brightness for astronomical objects are "Magnitude" - and, in the scale of things, this is pretty bright at 8.7

If we're posting links, try this one:
https://theskylive.com/florence-info

SultanOfSwing

Magnitude 8.7 is not exceptionally bright as far as astronomical objects go. That is just a bit too dim to be seen in binoculars, for example. Naked eye can see down to maybe magnitude 5-6 IF the sky is exceptionally dark and moonless, but certainly down to the 3rd or 4th magnitude in the average suburban sky. Hale Bopp (still one of my favourites) was magnitude 2, for example.

The really bright objects have negative magnitudes, like the Moon (-12-6), Venus (-4.4) and Sirius (-1.4).

Pulaski

I typed the URL manually and it had a typo.

It is now fixed.

Bahtatboy

Space cadet

Bahtatboy

Ah, right. What's the benchmark (zero)? Is it logorithmic? And why is something brighter more negative?

Yeah, I could googlewhack it, but you guys seem to know what you're on about.

SultanOfSwing

It is a logarithmic scale, with a decrease in magnitude of 1 corresponding to a 2.5 times decrease in brightness.

The reason for the negative numbers is due to the ancient Greeks organizing stars into categories, with 1st magnitude being the brightest and the sixth magnitude the dimmest. When we began to more accurately measure the brightness of stars, we tried to keep the same scale, but due to the logarithmic nature, we ended up having to use both numbers less than 1 (the bright star Vega has a magnitude of 0, for example) and negative numbers to make the classifications work. Or something along those lines anyway. So there isn't a benchmark as such, we just keep using larger (negative) numbers, which is why the Sun has a magnitude of -27

This is all apparent magnitude, or magnitude as observed from earth. There is also absolute magnitude, which is the magnitude of any object as observed at a distance of 10 parsecs (32.6 light years) from Earth. This puts the sun at magnitude 4.83, and the star Rigel in Orion, with an apparent magnitude of 0.12, so still pretty bright, has an absolute magnitude of -7.

steveq

Yes, its logarithmic, since its based on the human eye originally. 1 mag is roughly 2.5x brighter than the previous mag

Bahtatboy

Increase?

SultanOfSwing

One of them should have been increase, yeah. Doesn't matter which though