“They will see us waving from such great heights
‘Come down now,’ they’ll say.
But everything looks perfect from far away
‘Come down now.’ But we’ll stay.” -The Postal Service
Welcome back to another Ask Ethan! You keep sending in your questions and suggestions, and each week, I’ll pick one of my favorites to answer for you and the world. Today’s Ask Ethan comes from John, who asks one of the more fanciful and personal questions I’ve fielded yet, as he wants to know:
If you could jump into the Enterprise, or the Millennium Falcon, or whatever is your favorite faster-than-light starship, what in the Milky Way would you most like to get a good close look at, and why?
First things first, because we shouldn’t waste time arguing over the pros and cons of the ship: it would be Picard’s Enterprise, hands down.
Even restricted to our own galaxy, this is the closest science fiction has come to my long-term dream for humanity of a traveling, functional, self-sustaining and peaceful spacefaring civilization. Yes, the space cowboy fantasy of Firefly, the space rebels of the Star Wars saga and the space refugee drama of Battlestar Galactica all have their charms, but the Enterprise D of ST:TNG is the ship I’d most like to be aboard along the journey.
But where would I choose to go? There are a lot of fantastic candidates, and a far greater number that look like great candidates, but wouldn’t actually be.
For example, a sight like the Helix Nebula, above, colloquially known as the “Eye of God,” looks like it’d be a terrific candidate! Who wouldn’t want to see a dying Sun-like star up close, complete with the outstanding colors and resolution that we’d get from being right there. The evaporating gaseous globules would stand out in incredible contrast against the light-emitting gas, and it would be just glorious to behold.
- Incredibly long-exposure photography brings out faint details that would be either invisible or washed-out compared to the brighter parts of the nebulous region.
- This sight only appears to be compact because of our distance from it; from up close, it would be about a light-year in diameter, and would be far less bright and spectacular than the other stars in the night sky. And finally,
- Much of the detail that we see is because of the various filters we apply and highlight when we generate these composite images. In reality, what we’d see with our eyes would be far less colorful and have much less interesting contrast.
For example, here’s another planetary nebula, the Ring Nebula (M57), as it looks as imaged by a spectacular astrophotographer,
and here’s how that same object looks through some very good equipment, but to your naked eye.
The problem is that — to your own eyes — the bright things, and that means intrinsically bright but also where the brightness is concentrated, wash out the dimmer, intricate structures that you so enjoy seeing in your favorite space pictures!
So a number of fantastic classes of objects through a telescope just wouldn’t be spectacular up close and in person.
The star-forming regions and nebulae in our Universe, like the great Orion Nebula, part of an even larger molecular cloud complex? It’s not going to be nearly as impressive up close as it is from far away.
Supernova remnants, from the Crab Nebula to the Veil Nebula (above), are best viewed in the same way: from a distance.
You see, we tend to operate under this illusion that as we get closer to something, it always appears brighter and better, and that we can see more and better detail. The problem is, we’re not used to diffuse, extended objects. In these cases, if the brightness is (roughly) evenly distributed over a large area, as you get closer to it, each individual part doesn’t look any brighter, it just takes up a larger portion of the sky. For example, a nebula that’s twice as far away will have only one-fourth the brightness of the nearer one, but will take up one-fourth the angular size on the sky. You don’t really gain anything by going closer!
The problem is you want to see something like the image above, but what you’ll actually wind up seeing is more like the image below.
But if you can avoid the false temptation of these extended sources, you might realize that the truly amazing sights will come from collections of stars!
The nebulous region around NGC 3603 won’t appear this spectacular, but if you could fly in to the central core of stars, you would really be in for a treat!
But once you realize this, why settle for a star cluster, when there are more tightly bunched collections of stars out there?
This is Omega Centauri, also known as NGC 5139, the largest globular cluster in the entire galaxy. With a mass of over four million Suns in a radius of just 86 light-years, this would be my choice for where to take my star ship. Because once you’re inside, you’ll really notice two things: the great diversity and colors of stars inside, and how quickly they’re moving!
To highlight the color diversity and the density, let me just show you a little slice through the full resolution Hubble image at the center here.
To fly among those, to track their rapid, relative motions, to see the rare double-star interactions as they pass by one another, to have the possibility of catching a stellar collision in the act… this is where I would go. The only other place I’d even consider would be either the center of our galaxy or another, smaller black hole in the process of eating something,
or a star in the process/aftermath of a catastrophic outburst or explosion like Eta Carinae.
If you decided on one of those latter two, I wouldn’t be able to fault you (as it’s a matter of taste), but I think if I could spend all my nights gazing at the spectacular sights within our galaxy’s largest globular cluster, it would be a dream come true. It might not happen for me, but perhaps it will happen for humanity someday, if we begin to get it right.
And that will wrap up this week’s Ask Ethan; thanks for joining me, and I hope this answered your question!