What makes fireworks colorful?
It all thanks to the luminescence of metals. When certain metals are heated (over a flame or in a hot explosion) their electrons jump up to a higher energy state. When those electrons fall back down, they emit specific frequencies of light - and each chemical has a unique emission spectrum.
You can see that the most prominent bands in the spectra above match the firework colors. The colors often burn brighter with the addition of an electron donor like Chlorine (Cl).
But the metals alone wouldn’t look like much. They need to be excited. Black powder (mostly nitrates like KNO3) provides oxygen for the rapid reduction of charcoal (C) to create a lot hot expanding gas - the BOOM. That, in turn, provides the energy for luminescence - the AWWWW.
Aluminium has a special role — it emits a bright white light … and makes sparks!
The 2014 Astronomy Photographer of the Year competition has just released its cosmically awesome shortlisted entries. Capturing scenes across the solar system, galaxy, and beyond, the images are spectacular reminders that we’re all living on a “mote of dust suspended in a sunbeam,” as astronomer Carl Sagan famously put it in “Pale Blue Dot.”
In 1942 a young African American Ph.D. in mathematics, David Blackwell, interviewed for a teaching job at Berkeley. He was hired, but not for many years.
When finally invited to join the statistics faculty in 1952, several of Blackwell’s new colleagues told him there was a backstory to his failed application a decade earlier. It had been decided to offer him a position in mathematics, they said, but the wife of the departmental chair, who sometimes invited the faculty to dinner, insisted she would not have a black person in her house — and the offer was squelched.
Blackwell, who eventually became the first tenured black professor in the University of California system, shares this vivid memory in a 10-hour interview with the Bancroft Library’s Regional Oral History Office (ROHO). His life history is part of a recently completed oral-history series on 18 pioneering African American faculty and senior administrators, hired before the advent of affirmative-action policies in the 1970s, who broke barriers and laid the groundwork for those who followed.
[look of the hour]
It may seem quixotic or pointless to try to save the Kentile sign when so much of New York’s social and physical infrastructure is being dismantled. It may seem ridiculous to treasure an advertisement for a product that contained a harmful substance. It may seem presumptuous to try to require a private property owner to preserve a defunct piece of infrastructure for an admittedly ephemeral public good. But lots of people want to try.
"Words have power, letters have power," says Savage. "That’s how you claim something. It’s something we can share that has public meaning. I’m thinking of it as a monument. It’s something that symbolizes all these things. It carries all the weight of the culture. I think it is the de facto logo of Brooklyn."
Felix Baumgartner inspires us to push our limits. #WednesdayWisdom
This pen can scan any color in the world using a sensor and then matches it exactly using a five-color ink cartridge.
More info: http://bit.ly/1hMaPlx