370年11月2日 (2339 AD November 2 Old Style) Earth — Tourists are gathering from all the Twenty Planets today to see a natural phenomenon unique to the Earth: a total solar eclipse. The Earth and its major natural satellite, Luna, align periodically so that the system’s primary Sol is exactly blocked from view in a small region of the Earth’s surface, producing an effect known as a “diamond ring” for its similarity to a traditional ornament among the indigenous sophonts, before precisely blocking the star from view and revealing the extended stellar corona to the naked eye.
While satellite transits of a stellar primary are common to all inhabited worlds, and most known planets, the coincidence of size and orbital distance that produces the spectacular visual effect is so unusual that some religious groups on Earth point to it as evidence that the God or Gods have taken a special interest in the Earth.
A solar eclipse happens when the Moon passes between the Earth and Sun, blocking the Sun from view. Normally, this would simply be called a “transit”, and having one body transit the Sun from another is not really all that uncommon. But solar eclipses as we see them on Earth depend on a coincidence so unlikely that it’s entirely possible the Earth and Moon are the only pair of a planet and satellite in the entire Milky Way galaxy for which it happens.
It happens that the Moon’s diameter and distance are such that at least in certain parts of the Moon’s orbit around the Earth, the Moon as seen from Earth is exactly the same size as the Sun. For the part of the Earth’s surface that is on the direct line from the Sun through the Moon, the Sun is perfectly obscured, so that it’s only visible through mountain valleys around the edge of the Moon, producing an effect known as “Bailey’s Beads”.
Seeing the Earth from above. It has fascinated people for thousands of years. We would look at the mountains…
A friend, Todd Sharp, passes along this snapshot he took as he passed the Jet Propulsion Laboratory exit today:
The Curiosity Mars Science Laboratory hasn’t gotten as much press attention as it deserves, what with random elections and such going on. It’s a little quiet now, as it undergoes a “brain transplant” — its landing software is being replaced remotely with a new version. (And you thought installing Mountain Lion was a big job.)
In the mean time, let’s look at some of the most interesting images. This one, taken by the HiRES camera on the Mars Reconnaissance Orbiter, is my favorite so far:
That is a picture of the lander, on its parachute, taken from the MRO around 200 miles above the Martian surface, as it passed over at about a mile per second. Not a bad snapshot, eh?
Here’s an enhanced version of the picture:
Of course, we are more interested in the view from the Curiosity lander itself. Here’s a low-resolution video of the actual landing:
There will be a high-resolution version eventually — it takes a long time to transmit the pictures back.
(Oh, and I saw some people complaining that NASA used cheap low-res cameras — with a particular plaintive cry that they should have just taped an iPhone to it. The technical term for this complaint is “dumb.” The first pictures are meant to give quick feedback, ensure things are working, and confirm the landing. They’re purposefully low resolution, because it takes much less time to transmit. They’re literally thumbnails of the better resolution pictures to come.)
Finally, just before starting the “brain transplant”, Curiosity transmitted a full-color, high-resolution panorama. Here’s a glimpse, but you’re better off following the link to the whole panorama, as it doesn’t fit into PJ’s format well.
Today, we feature Dream Chaser, a private space plane being built by SpaceDev, a division of Sierra Nevada Corporation just a mile or two from my house. They made the first tethered flight tests out of Rocky Mountain Metropolitan Airport (locals will know it as Jefferson County Airport) on May 29th.
There’s something good waitin’ down this road
I’m pickin’ up whatever’s mine
Yeah runnin’ down a dream
That never would come to me
Workin’ on a mystery, goin’ wherever it leads
Runnin’ down a dream
(Running Down a Dream, Tom Patty, Mike Campbell, and Jeff Lynne)
“We shall not cease from exploration
And the end of all our exploring
Will be to arrive where we started
And know the place for the first time.”
– T.S. Eliot, Four Quartets
Rest enough for the individual man, too much and too soon, and we call it death. But for Man, no rest and no ending. He must go on, conquest beyond conquest. First, this little planet and its winds and ways. And then all the laws of mind and matter that restrain him. Then the planets about him, and, at last, out across immensity to the stars. And when he has conquered all the depths of space, and all the mysteries of time, still he will be beginning…
– Things to Come, H.G. Wells
Sometimes it’s worth remembering where we came from. This is the Nile Delta, image from the ISS. Somewhere down there was the Library of Alexandria and Cleopatra’s Palace, and 5000 years of human history.
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.