A large, cold, dilute gas of hydrogen and space dust collapses slowly under its own gravity, compression, heating, and fusion take place aided and abetted by shock waves, and then a star glows for millions to trillions of years.
That’s how it is usually explained but the numbers are hard to grasp. The clouds can be dozens of light years across, the gas pressures are lower than the best vacuums on earth, the shock waves aren’t the kind we associate with sonic booms, and it can take tens of millions of years to get the party started.
Yet it happens and we are here because of it. The details are very toughsledding but equally interesting.
Introductory Astronomy: Star Formation and the Lifetimes of Stars
Big tankers tie up offshore and disgorge their contents into brightly lit and mostly inscrutable refineries. This sixty year old film by Shell Oil neatly explains the chemistry, chemical engineering, and physics of distillation that takes gives us our gasoline, diesel, oils, and waxes. In a different setting, it also gives us many different kinds of beverages.
39 years ago today, Voyager 1 took flight on its Grand Tour. It has gone farther than any other man-made object in history and won’t stop until it reaches the stars long after we and all that’s important to us are dust. Idealism wasn’t for chumps back then. Or maybe it was. JPL and NASApost the mission data from all these interplanetary missions and it is all free.
A lot of my research over the years required cooling objects to ‘freeze out’ some phenomena in order to study others. Liquid helium was often essential to get to these temperatures. Its a fascinating material quite apart from its practical value as a refrigerant. Alfred Leitner’s beautiful demonstrations from 1964 give a glimpse into a liquid that continues to be actively studied by many laboratories.
Astronomy buffs should enjoy Chris Impey’s free online courses offered through Udemy and Coursera. One interesting feature of the Astronomy State of the Art course is his regular online office hour where he takes questions submitted in real time as well as by email. The questions are invariably very good, spanning terrestrial, planetary, galactic, and cosmological topics. Impey takes time to respond thoroughly. The live sessions are broadcast on a Google Hangout and archived on Youtube. Here’s a collection of them.
Update: 17 March 2016
The seminar series including music performances will be webcast live this year. Details will be provided in the next few days
Image courtesy of the Carnegie Observatories
The Carnegie Observatories of Pasadena have announced their 2016 Lecture series, beginning in early April 2016 at the Huntington Library in San Marino. There will be four talks by learn’d astronomers on the Las Campanas observatories, Planet formation, Exoplanets, and the lifecycle of Galaxies. Each will be preceded by music performances by students from the Colburn School. The talks are free but reservations are required. Doors open at 6:45pm, talks begin at 7:30pm.
Visit the Observatories’s Youtube Channel for rigorous yet accessible talks from previous years. The only downside is that the events are on Monday nights, a hell of a schlep for those of us in the South Bay.
Carnegie Spring Lectures at the Huntington Library
1151 Oxford Road, San Marino
All Lectures are in Rothenberg Auditorium.
Monday, April 4th 2016 Las Campanas Observatory: A Southern Window on the Universe
Dr. Mark Phillips Director, Las Campanas Observatory, Associate Director for Magellan
Carnegie Institution for Science
Monday, April 18th 2016 A Short History of Planet Formation
Dr. Anat Shahar Staff Scientist, Geophysical Laboratory
Carnegie Institution for Science
Monday, May 2nd 2016 Exoplanets
Dr. Kevin Schlaufman Assistant Professor of Physics and Astronomy, Johns Hopkins University
Carnegie-Princeton Fellow Carnegie Observatories & Princeton University
Monday, May 16th 2016 The Secret Lives of Galaxies
Dr. Katherine Alatalo Hubble Fellow,
I had the good fortune to spend time as a kid at the Lawrence Berkeley Laboratory. My father worked there and I later did undergraduate research projects in labs housed there. I’d often pass through a certain hallway where astronomer Jerry Nelson was advocating a new way of building large telescope mirrors without investing in one gigantic piece of glass. His approach: Lots of small pieces of glass, prestressed in jigs, polished, and released with each forming a part of the mirror surface. The trick was to stress the pieces so that they’d assume the required precise shape when the loads were removed. Tile these pieces together and go as large as needed. I never met Nelson but I read the posters by his labs carefully, wondering if and how it could work in practice. I also bumped into Dr. Richard Muller, my Modern Physics professor one day in that hall. A man of very eclectic tastes, he changed subfields often and he’d moved from radioisotope dating to observational astronomy. He showed me a device that could convert 80% of the visbile light falling onto it into electrons – one of the early CCDs that are now everywhere. At the time, CCDs were thought to be the next great thing in computer memory. Muller told me that it was in fact the future of astronomy. There were two revolutions in that one hallway and I had only the dimmest awareness of what either meant.
Today, there are many telescopes with unfathomably large collection areas thanks to Nelson’s innovation and persistence. CCDs and electronic detectors at other wavelengths are approaching perfection in their light detection ability, photographic plates are a thing of the past, and telescopes can now go into space because there’s a practical way to get information back to the ground.
European Extremely Large Telescope (all images courtesy Wikimedia)
Of course, not every modern telescope is made from segmented mirrors and any actual design is always subject to thorough, brutal trade studies that determine what’s best for the science. Prof. Roger Angel at the University of Arizona has perfected making mirrors as large as 8m in diameter. That’s a whopping 315 inches, 150% as large again as the 200 inch gem at Palomar. The Large Synoptic Survey Telescope (LSST) currently under construction has selected one of these as its primary. A friend on the project says it is actually two mirrors of the three that will ultimately make up the telescope that will photograph a huge chunk of the sky routinely, generating 15 terabytes of data a night.
As if LSST were not enough, three 30-m class telescopes are being developed for looking at faint objects in a much smaller field-of-view. There isn’t a way to make a single aperture that size so all three will require segmented mirrors. The Giant Magellan Telescope and European Extremely Large Telescope will be built Chile, the Thirty Meter Telescope will be built in Hawaii next to the Kecks, built to Jerry Nelson’s concepts. All are set to see light in 2022. We’re looking at a Platinum Age for astronomy and our understanding of the Universe. I envy, in a positive sense, those who get to work on these eyes.