The Infinite Canvas: Hubble Deep Field
So the editors passed on my original title for these posts; after some discussion and a small Facebook survey, I’ve chosen a new title — The Infinite Canvas — for this continuing series of space art and astronomical photographs. Thanks to Garret Moore for the title, and to my colleagues in the International Association of Astronomical Artists for all their suggestions.
As something suited to introducing the new title, I’m going to pull out one of my favorite pieces of space po… — er, of sky photography, the Hubble Deep Field.
Of course, this is hardly new — but it is, I think, the most profound thing I’ve seen in my entire life. You see, this image, taken over the course of many many hours’ exposure, is about one quarter of the whole Hubble Deep Field image; the whole image is about one minute of arc (1/60th of a degree) across, so this image is about 15 arc seconds across.
To put that in perspective — if you took a dime, and held it up for a friend 750 feet away — call it two and a half football fields — that dime would cover about the same angle as this image. Looked at another way, that’s about 3 ten-billionths of the whole sky.
Now look at the image: two of the bright spots have X-shaped lens flares. Those are stars in our Milky Way Galaxy. Every single bright spot in the image, other than those two, is a whole galaxy, most of them as big as the Milky Way or bigger.
And every single galaxy has hundreds of billions of stars, many of them just like our Sun.
And,we’re now learning from studies using a new technique called gravitational microlensing, every star has, on average, at least one planet — closer to two, in fact.
How many galaxies are in that image? A hundred? A thousand?
Take that times 300 billion.
Take that times another 3 billion. Roughly.
And take that times 2.
And that is how many planets there are in the Universe.
Molte grazie!
The images from HST are each like the first sentence in a new adventure book, with the advantage that the adventure is real.
“And that is how many planets there are in the Universe.”
That we can see.
True, I didn’t even include a guess for “rogue planets” and substellar objects. The neighborhood is getting downright crowded.
Seen this?
http://xkcd.com/1071/
*sigh* It was going to be tomorrow’s IC.
What?! You really thought no one would know about it?!
No, and I didn’t actually change my mind.
And yet, look at all the incredible luck, circumstances, and events that led to life on Earth. So, are we looking at a universe teeming with life, or the odds?
I think the most frank answer is “we have no idea.” I think it really looks like on Earth there’s life anywhere there is liquid water — even if it has to be a very strong brine to keep from freezing, or under miles of sea water to have enough pressure to keep it from boiling, or if the liquid water only happens for a few days a year, or if the radiation flux would kill a person in minutes.
But that’s only on Earth.
But then we know that Earth and other planets and asteroids occasionally exchange chunks, so it’s entirely possible that either we’re seeding other planets or other planets seeded us.
My own feeling is that this is a Universe that does life — and it’s going to be everywhere, and even in forms we wouldn’t currently recognize as life. But that may be as much a religious feeling as a scientific one.
Dad was a noted rocket scientist and got a big kick out of Carl Sagan being able to build celebrity status looking for something that Dad felt was going to be almost impossible to find. That was in the mid-late 60′s.
Fast forward to SETI, radio telescopes and Hubble, and we sure have learned a lot, but we have also learned how lonely our sector, at least, of space is.
It really is amazing. We need to keep the spirit of exploration alive. I agree completely. The more we know, the more we realize we still don’t know much at all.
I WILL figure out a way to go visit those other stars.
There is no WAY I’m going to accept being caged in one small gravity well forever.
Orion
Take me with.
“And that is how many planets there are in the VISIBLE universe.”
We don’t know how far it goes, only how far we can see.
Actually, Charlie, I think your estimate is a MINIMUM number of planets. And yes, I agree, I think we’ll find life anywhere it can exist. My new definition of life is the ability to transform and store energy, and to reproduce. I’m really curious about what form some of those life forms will take.
I’ve often wondered why we haven’t (to my knowledge) been contacted, or even detected, other life forms. It could range from lack of development, background noise, signal strength, and frequency to a totally different form of communication and data sharing than anything we know. I guess we won’t find out for sure until we get out there…
What’s going to cut deeply into the inhabitable planet actual numbers is how many occupy the goldilocks zone. That will be a tiny fraction of the whole, as it is in our solar system.
That will still leave millions, I suspect, in just our galaxy.