We had a rainbow this afternoon. It was a pretty good one, a full arc right down to the ground, with fairly bright colours.
We live across from a city park, facing east-ish, and rainbows usually hover in that area of the sky. Very very pretty. There is something magical about a rainbow, even though its science is well-known. Light rays split into colours while passing through raindrops. Simple. The result, though, looks (to me) like a miraculous revelation, a sign from above telling you you're on the right track.
Rainbows must occupy a primal place in the human psyche - how else to explain the wide variety of definitions and links I found from a very superficial look 'round the web.
The Irish pot of gold at the end of the rainbow is well known; but I wasn't aware that in northern European cultures, rainbows were considered the Bridges of the Dead, or bridges to the otherworld.
Rainbows lend their name (and mystique) to a vast array of objects and concepts. We have rainbow trout, rainbow lizards, the Rainbow Bridge connecting Canada and the U.S. at Niagara Falls, the Rainbow Bridge National Monument in Utah (the world's largest natural bridge), the Rainbow Room (formerly a restaurant in New York City), and the rainbow division of the Girl Guides (five to seven year old girls - I think it's a British thing.)
Rainbow Six is a strategy game based on Tom Clancy's novels; Rainbow Brite, a 1980's cartoon show; Reading Rainbow, a much better children's show; Rainbow Hotels, a Norwegian chain; the Rainbow Award, presented for GLBT web excellence; Jesse Jackson's "Rainbow Coalition"; rainbow is also a brand of vacuum cleaner and the name of albums by Mariah Carey and Neil Diamond.
Then there's "Over the Rainbow" by Judy Garland, the "Rainbow Concert" by Eric Clapton, "Rainbow Country" by Bob Marley, "Dance of the Rainbow Serpent" by Santana,   ET cetera.
I also found out that Rainbow Sandals are "the world's best sandals"; there is some weird Native American hippie-cult thing called the Rainbow Family; and, sadly, the mythical Rainbow Bridge is reborn in cyberspace as a sort of therapeutic pet heaven.
By far the most intriging reference to rainbows came from a review of this book:
UNWEAVING THE RAINBOW: Science, Delusion,
and the Appetite for Wonder
by Richard Dawkins.
The author, discussing science and poetry (or something) referred to rainbows as   "barcodes in the stars".   It just doesn't get any more romantic than that.
While we're looking upwards..
More NASA stuff, more photos taken from satellites; the object of study is the earth:
Earth's 4.5-billion-year history is a study in change. Natural geological forces have been rearranging the surface features and climatic conditions of our planet since its beginning.
Today, there is compelling scientific evidence that human activities have attained the magnitude of a geological force and are speeding up the rates of global changes. For example, carbon dioxide levels have risen 25 percent since the industrial revolution and about 40 percent of the world's land surface has been transformed by humans.
Human activities are on the same scale of magnitude as a geologic force? I never thought of it quite like that, and it does bring the point home!
This is part of a fifteen year study of data collected by a series of satellites, designed to study climate and environmental change. Unlike the Hubble, these instruments point towards earth; but the resulting images are no less astounding in their stark beauty.