Starship Asterisk*

I actually work out a BV absolute magnitude of -16.8 for Eta Carinae's 1843 outburst. This weighs in at around ten million solar. This compares quite well with some supernovae.

I also see 4x Canadian and 1x Japanese. I was expecting something like 1,322 American and possibly half a Canadian if the Americans haven't covered it up with their own. Those people like flags. A lot.

It appears to be a slightly distorted contrail from a plane in circular holding pattern. It's much larger than naturally formed annular clouds and the kicker is that it's far beyond the foreground mountain, but below the cloud deck, and so is quite low but also very large, just what you'd expect fro...

The colour of the sky very much depends on time of day and local conditions. On Earth we're used to Rayleigh scattering giving us a lovely blue sky. On Mars, however, Mie scattering dominates most of the time, giving a pinkish sky and bluer sunsets. A Martian day that's exceptionally clear of dust (...

Download and install Stellarium. It'll show you on your computer screen what you can also see outside, and can identify most objects.

I didn't see a damned thing from South Yorkshire and I was out observing for a cluster of Iridium flares at the time.

Also that phone image looks really, really fake.

As far as I know, "impact basin" is a specific term for a crater much larger than 20m!

Then how do we ever move beyond existing theory? If everything has to happen within existing theory, doesn't that preclude being able to move beyond it, by definition? Would you say that relativity is 'within the bounds' of Newtonian mechanics? Thing is, everything has to happen within existing the...

Almost certain that "Mystery 1" is atmospheric gravity waves, especially given that there are mountains very nearby. Mystery 3 is quite obviously a constellation of satellites flaring. The second one could be a failed missile or rocket launch/test, the fan shape is can be formed by a disin...

I've actually done this with a very low power laser and welding glass. I wanted to know if I could see the laser being brighter or darker as I moved along it. So I vote based on that.

Edit: Beyond, that's just an artifact of how the diagram is drawn. You're seeing a side view, not a top view.

Even if the photon passes through only one slit (e.g. experiments done with single photons at a time), it still produces an interference pattern as we can consider it to be interfering with virtual photons. This is simply a high-tech take on the one photon at a time experiment which has been done an...

The state of the impactor is already known: A rocky body and not, like the last two, a cometary object. The lack of a ring around the impact site, caused by the low density of a comet, tells us this impactor was solid as far as the lower cloud decks.

No. AFAIK there are no candidates for captured binaries. The possibility of a capture through a 3+ body system is understood, but is extremely unlikely in practice. While not stars, we believe Triton (Neptune) was captured exactly this way. Neptune has a distinct lack of larger moons and Triton was...

I think that this statement depends on how you define "gravitational bound". All massice objects are affected by others' gravity. If there's a lot of empty space around the cluster, the gravitational bound of a galaxy to the group is stronger because there's no opponent. Otherwise if ther...

Not a vote for any (I voted for "Mystic Mountain") but a vote against. NO RAW IMAGES. Seriously. APOD, to me, is an example of the best of astronomical images. Raw images plain aren't. If I want raw images, I know where to get them and what news sources will give me them. If I don't know t...

You shouldn't hotlink images from Something Awful. They tend to get very NSFW very quickly.

In this case, I don't believe the OP indeed has provided enough for anyone to solve it by any means other than brute force or dumb luck.

Though I personally am yet to try. I'll give this a go tomorrow when RL is less of a burden.

I think we need a standard size for crops, some are just too small, like this one, to make for a reasonable challenge.

Making a stupidly small crop just makes it easy on the challenge poser.

That very much depends on your definition of "part of". We are gravitationally bound to it but this was not always the case[1] and will not always be the case[2]. For example, between us and the Virgo Cluster is the Canes I Group and the M81 Group. [1] We're on the very outskirts, which li...

There are two schools of thought in galaxy formation (no, you can't escape it!). The first one I'll discuss is "stars came first" that a cluster of stars used their gravity to draw in more material and so set off galaxy formation. The central black hole simply sank there and absorbed more ...

The Javascript code is here if anyone wants to use it locally.

makc's PHP version is more elegant than mine (and should be used as first preference), but won't work on some servers (such as mine!) which don't let PHP play with headers. Code for that is here.

No, it doesn't.

For talking purposes assume the non-exploding star is like the Sun and 60 Sun radii apart from the supernova star. That's difficult since a star like the Sun can never explode. What possible calculations and/or logic could be used to estimate whether the subject star increased or decreased in size ...

Random APOD (Javascript version, use this) Random APOD (HTML version, doesn't work well with browser caching) Won't work right during some hours as APOD doesn't use UTC. It may give you "today" by UTC but APOD is still "yesterday". I should imagine that to be fairly rare, though.

That gives me an idea. I could do this on my web server.

Coding time!