Today is July 4, Independence Day, a national day of celebration. Go out and enjoy the early evening after sunset - and before the fireworks start.
You will find ever brilliant Venus in the western sky after sunset. Saturn will be a little past due south at 8 p.m., and mighty Scorpius the Scorpion with its bright red star Antares will be ascending from the southeast.
If we could transport ourselves back to July 4, 1776, we would find dark skies, with no light pollution in the Presidio San Agustín de Tucson that Hugo O'Conor established the previous summer.
On July 4, 1776, the moon was just past full, rising at 8:20 p.m. and setting the next day at 9:42 a.m.
We don't have daylight saving time in Arizona - for which I am personally happy. Nevertheless, one of our American heroes, Benjamin Franklin, is credited with first suggesting the idea in 1784. In Franklin's day, no one could have guessed there would be a future University of Arizona with scientists operating a spacecraft on Mars.
In 1776 the source of the sun's heat and light was unknown, and no one knew the distance to other stars. The nature of stars themselves was unknown, though some guessed they might be faraway suns.
What would Benjamin Franklin think if he were transported to our times? Would he be appalled by our wars and environmental abuses, or would he marvel at our scientific knowledge and technology? No one knows, but we do know he would recognize the same familiar friends in the night sky.
Did you know
Tucson fell under the jurisdiction of the United States after the Gadsden Purchase in 1854. Arizona became an official territory in 1863, and the 48th state in the Union in 1912.
If you go
Friday's meeting of the Tucson Amateur Astronomy Association will start with a talk about objects that can be viewed in the summer night sky.
That will be followed by Amanda Brady Ford, a graduate student at the University of Arizona, who will discuss "The Circum-Galactic Medium: The amazing, incredible, rich region around galaxies."
In the big bang, all the universe created was hydrogen and helium. Every other element (from the oxygen we breathe, to the iron in our blood) had to come from a star. Yet today, when we look in the universe, we see huge amounts of these heavier elements far, far away from stars, far away from planets, even far away from galaxies. How did they get there? And what does it mean for the evolution of galaxies and the universe as a whole? To answer those questions, Ford will talk about supernovae, galactic super winds and cosmological inflows, as well as present the latest results from the Hubble Space Telescope and state-of-the-art simulations. Ford recently returned from two conferences in Europe, where she was selected to present her work. She earned her bachelor's from Harvard University in astronomy and astrophysics.
The free event starts at 6:30 p.m. in Room N210 of the Steward Observatory, 933 N. Cherry Ave., on the University of Arizona campus.
The moon is a waning (growing smaller) crescent. New moon is Monday. Tonight sunset is at 7:34 p.m. with astronomical twilight ending at 9:14. The moon does not rise until 3:21 a.m Friday.
Contact Tim Hunter at email@example.com Source: tucsonaz.gov