Astronomy.com blog : Daniel Pendick, telescopes

Updated: Historical telescopes at the Adler Planetarium

Daniel Pendick — Thu, 21 May 2009 19:20:00 GMT

***Images updated.***

Next week, you can check out the rich collection of astronomical instruments at the Adler Planetarium in Chicago. In celebration of the 400th anniversary of the telescope, the planetarium opens its a new exhibition, “Telescopes: Through the Looking Glass,” on May 22. The show spotlights technology used to gather information about our universe since Galileo’s day and includes hands-on interactive exhibits.

The trumpet-shaped telescope is a rare type with few surviving examples. Its distinctive feature is a front end that flares outward to the instrument’s objective lens. The Adler show will take you from the 1600s, when this beauty was made in Italy, to the reign of the Hubble Space Telescope, now being refurbished in orbit by a space shuttle crew.

Dating from around 1630, this beautiful Italian refracting telescope is the only early telescope found outside of Europe. Part of the Adler's world-famous Mensing Collection, this rare trumpet-shaped telescope's main tube tapers outward from the eyepiece. ©Adler Planetarium]

This 1977 pocket telescope, created by noted English craftsman Peter Dollond, is encased in tortoise shell inlaid with silver. The tubes are made of pasteboard with an interior surface that's matte black to reduce stray reflections. Red leather tooled in platinum covers the single draw, with the overall design based on leafy vines. ©Adler Planetarium

Owning a Dollond telescope carried a great deal of social weight. This elaborately decorated piece from 1843 is made of gold-plated sterling silver. The main tube shows raised scrollwork and foliate decoration, its case red Moroccan leather with elaborate gold tooling. A Turkish noble likely commissioned it. ©Adler Planetarium

William Herschel, a German musician turned astronomer, discovered Uranus in 1781 using a reflector identical to this 7-foot instrument made in 1788. Herschel's passion for astronomy led him to build the most powerful telescopes in the world. He also invented a mount that allowed the eyepiece to stay at the same level while the tube and mirror moved to locate celestial objects. ©Adler Planetarium

AT LAST! The next-next big thing in space telescopes?

Daniel Pendick — Thu, 16 Apr 2009 16:39:00 GMT

Astronomers eagerly anticipate the final Hubble Space Telescope (HST) servicing mission, set to blast off May 12 from NASA's Kennedy Space Center in Florida. And they are already hard at work designing the observatory that will take over after Hubble sees its final light.

Hubble is, in the lingo of telescope engineering, a UVOIR instrument: Its 2.4-meter light-collecting mirror samples wavelengths of light in the ultraviolet (UV), optical (O), and near-infrared (IR).

The James Webb Space Telescope, slated for launch in 2013, will have a much larger light-collecting mirror — 6.5 meters — than Hubble. But it will operate in the infrared.

No one knows how long HST will continue to function after the final servicing mission. It’s been in space since 1990 — 19 years and counting.

HST’s presumptive successor is ATLAST: the Advanced Technology Large-Aperture Space Telescope. I came across a detailed report on the telescope, authored by a large group of scientists and engineers from companies and scientific institutions — including Marc Postman of the Space Telescope Science Institute.

The Postman report is part of Astro2010, the ongoing “decadal survey” in astronomy and astrophysics. Every 10 years, the National Research Council of The National Academy of Sciences undertakes the surveys to recommend scientific priorities for the coming decade. ATLAST is just one idea vying for support.

ATLAST’s primary mirror would be 8 to 16 meters wide. The 8-meter concept (pictured above) assumes a solid mirror, like that of HST. The 16-meter version would have to be an unfolding assembly of segmented mirrors, like the one on the James Webb Space Telescope. Postman’s group projects the telescope could be ready for launch by 2025. Technology development, design, and planning would cost hundreds of millions of dollars.

For one thing, ATLAST would have the ability to actually detect oxygen, ozone, water, and other possible life signs (“biosignatures”) in the atmospheres of extrasolar planets. It could probe deeper than ever into the processes that create stars. And, we can assume, it will send home spectacular images of the cosmos in even greater detail than HST has captured.

Image credit: Frassanito & Associates, Inc. and the Future In-Space Operations Working Group

“400 years of the telescope” documentary airs

Daniel Pendick — Wed, 08 Apr 2009 14:27:00 GMT

Telescopes have extended the human senses to unimaginably distant and inhospitable parts of the universe. A documentary beginning to air this week on public television stations in the United States tells the story of the telescope and its unveiling of the cosmos — starting with that simple little tube Galileo pointed at the Sun, Moon, and stars.

The 60-minute documentary is called 400 Years of the Telescope: a journey of science, technology, and thought. Writer/director Kris Koenig of Interstellar Studios produced it with support from the National Science Foundation. Check out www.400Years.org for times when you can watch it in your area.

One of the film’s strengths is the narration by astronomer Neil deGrasse Tyson, director of the Hayden Planetarium at the American Museum of Natural History on Manhattan's Upper West Side. He’s a master explainer and keeps the flow moving briskly through a broad panorama of people, places, and telescopes.

I also appreciated the writing. It’s clear, accurate, and compelling. Tight editing and the music feed the flow.

Another bright spot for me was the handling of the historical period in which the infamous “Galileo affair” occurred. Galileo’s encounter with the Catholic Church is often oversimplified. The historical section includes commentary by two world-class historians of science, Owen Gingrich and Albert Van Helden (the latter also a member of the writing team for the film).

The core of the film is a tour through the evolution of telescopes as a tool for astronomy. You’ll see many of the world’s greatest instruments and hear from the scientists who developed them.

The tour covers the invention of astrophotography (which banished the human eye from astronomical research) and the birth of astrophysics.

The story continues up through the discovery of “dark energy,” the mysterious quantity invented to explain why the expansion of space appears to be speeding up. The film also introduces us to megascopes on the horizon, like the Thirty Meter Telescope.

The sheer number of different stops in the tour may seem overwhelming to some viewers. But the payoff includes a lot of insight into what astronomers do and how they do it. All seen through the lens of the things they do it with — telescopes.

Image courtesy Interstellar Studios

Related:

Video: "The day Galileo changed the universe, part one," with Astronomy magazine Editor David J. Eicher
Video: "The day Galileo changed the universe, part two," with Astronomy magazine Editor David J. Eicher
Blogs: International Year of Astronomy
Blogs: Galileo

The quiet Sun

Daniel Pendick — Fri, 03 Apr 2009 19:23:00 GMT

Last summer, my colleague Michael Bakich, a senior editor at Astronomy, kindly gave me a special filter that fits on the front of my 4-inch Celestron NexStar, thus allowing me to observe the Sun without turning my eyeball into a poached egg.

I looked at the Sun with the new setup. Nada. Nothing!

Thanks to this cool graphic just released by NASA, it’s clear why the Sun is so, well, boring to look at lately. We are in a deep “solar minimum,” a period in the 11 (or so) year sunspot cycle where things are as quiet as an umbrella shop on a sunny day.

Dramatic statistic time: As of March 31, there were no sunspots on 78 of the year's 90 days (87 percent). For more details, check out this well-done little report from Science@NASA.

Image credit: NASA/MSFC/Hathaway

Join the pulsar hunters and work from home

Daniel Pendick — Thu, 26 Mar 2009 19:13:00 GMT

“Wanted: a few hundred thousand computers with a little spare time on their hands.”

That’s the basic job qualification if you (and your personal computer) want to join Einstein@Home, a massive international project that uses donated personal computer time to crunch data for real scientists. The project has been going on for several years. This week, Einstein@Home announced it will begin to analyze data from a new source: the giant radio telescope at Arecibo Observatory in Puerto Rico. It’s not too late to get into the action.

Einstein@Home, based at the University of Wisconsin-Milwaukee (UWM) — a short drive down I-94 from Astronomy headquarters — and the Albert Einstein Institute (AEI) in Germany, is one of the world’s largest public volunteer distributed computing projects. Some 220,000 people in 209 countries have signed up for the project and donated time on their computers to analyzing data collected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and GEO 600 (in Sarstedt, Germany) for gravitational waves.

Powerful astro-events, like black-hole mergers, should generate ripples in the very fabric of space-time (gravitational waves). Einstein@Home uses the collective number-crunching power of thousands of computers to look for patterns of gravitational waves hiding in data captured by LIGO and GEO 600.

The researchers with Einstein@Home will be searching the Arecibo data for a special type of astronomical odd couple that generates gravitational waves: a spinning neutron star, or pulsar, orbiting a black hole. Both objects spring from the collapse of massive stars.

Previous methods could find such binaries in radio data if they orbited each other every 50 minutes or longer. Using the collective computing power of its volunteers, Einstein@Home will be able to find pairs with orbits as short as 11 minutes.

Many dedicated amateur astronomers contribute to various kinds of research, like the study of variable stars and discovering and tracking asteroids and supernovae. But if stargazing isn’t your thing, here’s a way to do some astronomy by essentially doing nothing.

Well, not exactly. You do have to sign up for Einstein@Home and install some software. The project team expects to spot at least a few new pulsars per year.

To find out how to participate, go to einstein.phys.uwm.edu.

Caught: a satellite on amateur astronomer’s first video?

Daniel Pendick — Fri, 20 Mar 2009 14:05:00 GMT

Check out this video from Astronomy reader Robert Massey of Fort Worth, Texas. Look to the top left of the grouping of four bright stars, at about the 11 o’clock position. A blob appears to move to the left.

The video shows an object — a satellite or perhaps an asteroid? — tumbling through the field of view of Massey’s Meade 12-inch LX200 telescope. At the time he was observing M42, the Orion Nebula.

In his own words: “I have been behind a telescope for a little over a year. I recently bought an LX200 and started taking video with it. On March 2nd at 8:17 p.m., I was looking at Orion and saw an object flying though the pic. I hit record and looked up to see nothing. The video shows the item tumbling. I’m just wondering if this is normal or may be of interest. Thanks.”

I received that e-mail last week. Intrigued, I asked him to send me the video clip. At first I didn’t see anything and started to wonder if Massey was mistaking electronic noise in the camera for something real. He sent a lightened version of the clip to me and, sure enough, there is something in the sky.

Like I said, maybe a satellite or an asteroid. Who knows? The coolest thing about this incident is how it closes the sometimes-invisible circuit between the magazine and our readers.

Massey got interested in telescope video because of an article we ran in November 2008 on amateur astronomy with a web cam. He hot-glued a web cam onto a piece of tubing to adapt it to his telescope. He used free software available on the Web to run it.

Massey’s no engineer, but he knows how to fit tubes together — he’s a plumber. He bought his first scope only a year ago at a thrift store. “I like galaxies the most,” he said, “but have not been able to photograph them well yet. I’m planning to get out to a dark-sky location soon and try again. But nebulae, planets, and planetary nebulae are my other interests.”

For now, with his new LX200 and a backyard that is “not all that dark,” Massey is exploring the universe. We are glad to have been of assistance.

Our man in Cape Town III: Big radio telescope science

Daniel Pendick — Tue, 10 Mar 2009 19:22:00 GMT

In recent blogs, I introduced you to Benne Holwerde, a researcher at the University of Cape Town in South Africa. He’s on a team of scientists building a new radio telescope called MeerKAT (Karoo Array Telescope). Holwerde and his group hope MeerKAT will solidify South Africa as the host site for the Square Kilometre Array (SKA), an even-larger radio telescope. The SKA will be the world's biggest radio telescope, and it will be built in either South Africa's Northern Cape province (with outstations elsewhere in the country and spread across eight other African countries) or in Australia (with, possibly, outstations in New Zealand).

Here’s another report on the project from Holwerde.

SKA continuum conference
Recently we had a grand get-together of big names in astronomy here in Cape Town. There were a lot of high-level policy meetings about the Square Kilometre Array (SKA). I did not go to all of these, but there was a science conference in the mix as well, and I was definitely attending that. The meeting focused on one of the types of science we will be able to do with the SKA and its pathfinder projects MeerKAT and ASKAP: the radio continuum, which includes emission all across the radio spectrum due to highly energetic electrons.

Radio continuum is not my area of interest in radio astronomy — I study the 21-centimeter emission line of hydrogen — but it is very relevant for the eventual design trade-offs that will happen with both the SKA and the pathfinders. That discussion was happening in part during the coffee breaks, lunches, and dinners.

It is a hard call to make. The telescopes are put in a specific pattern. The array’s efficiency at observing the hydrogen emission or the radio continuum depends on the pattern of dishes. After the dishes have been put in place, it is nearly impossible to redesign the pattern. There were many talks and discussion emphasizing that we need to get it right initially.

Talks centered on the type of science that is on the horizon with such big radio telescopes. One of them was given by a friend of mine, Erik Murphy, now at Caltech. He did his Ph.D. on the relation between radio continuum and far-infrared emission, both the result of newly forming stars. The relationship is so tight that it will be worthwhile to track the rate galaxies were forming stars in the earlier universe with radio continuum emission. We really don’t know when and where most of the stars in a galaxy were made. Far-infrared observations of the distant universe are hard to obtain. You need space missions for those. But we might be able to use the SKA to probe star formation in the earlier universe based on the radio emission.

Some other possible science had crept into the talks as well. Recently, pulsar timing has emerged as a possible way to check Einstein’s general theory of relativity in extreme environments. Very cool science.

There was also a talk about using the information in the 21-cm emission line together with new NASA and ESA missions such as the Herschel Space Telescope. I would have cheered the guy on a little more, except that I think he also proposed to look at several places in the Northern Hemisphere. Oops. All the radio telescopes we were talking about are in the Southern Hemisphere.

And then there was the dinner. We bussed out to the wine lands near Cape Town (only 30 minutes or so, traffic permitting) and dined with the whole conference at Spier, one of the biggest wineries there. Going to a wine farm for wine tasting and lunch is one of my favorite things to do here. My rule is the smaller the winery, the better — but if you’ve got 150 or so people, Spier was a good way to go. This is South African cuisine at its best. Great if you like meat, especially game.

One of Spier’s gimmicks is a lady that gives you African face paint (lots of little dots), so that explains the photo of me here. The joke of the evening was that everyone had a different telescope design on his or her face. A prerequisite to a good conference is good food (and coffee) and this SKA 2009 Continuum Workshop was a great success (both culinary and scientific).

So there are these three almost completely different science topics we will be able to do with these telescopes as soon as they are built — 21 cm hydrogen, radio continuum science, and pulsar timing. The big discussion now is how do we configure the telescope so it can accommodate all three pursuits. I’ll hear more about that soon, I expect, because the first foundations for KAT-7 (the first seven dishes of MeerKAT) have already been poured.

Previous posts:
Our man in Cape Town II: What science could MeerKAT do?
Our man in Cape Town: Benne Holwerda wants to build the biggest radio telescope in history

Our man in Cape Town II: What science could MeerKAT do?

Daniel Pendick — Fri, 13 Feb 2009 20:27:00 GMT

In a recent blog, I introduced you to Benne Holwerde, a young researcher at the University of Cape Town in South Africa. Check out the view from his office in the image at right. He’s on a team of scientists hoping to build a giant new radio telescope called MeerKAT (Karoo Array Telescope), a project Holwerde and his group hope will solidify South Africa as the host site for the Square Kilometre Array. Here’s another report on the project from Holwerde.

We're still busy with the “science case,” a description of what science we think can be done with MeerKAT. The case splits into different sub-fields. Here at the University of Cape Town, we have a group working on research you can do by observing the 21cm emission line of neutral hydrogen.
There are all kinds of different astrophysics you can address with the information in the 21cm line, both how nearby galaxies form and behave and how larger structures of galaxies look. This is what the Cape Town group is working up in its science case.
Nearby galaxies
What does the gas reservoir of spiral galaxies look like? How does the gas move and clump? Where is it lumping together to form stars? Do we see smaller galaxies fall into big ones like our Milky Way, forming new parts of the galaxy? How many dwarf galaxies are there anyway? These are the kind of questions we hope to address with a survey of nearby galaxies using MeerKAT.
Great Attractor
One of the nice things of the 21cm line is that our own Milky Way is transparent for it. In optical or infrared, there is too much absorption by dust in the disk to see much except what is in our own galaxy. But in the 21cm line radio observations, it will be possible to detect the large structures hiding behind the bulge of the Milky Way. There must be something there.
For some time now, we’ve known that the biggest gravitational pull in the local universe is being exerted from somewhere behind the bulge. This Great Attractor is some superstructure made of galaxies, but we scarcely know what it looks like. MeerKAT is situated beautifully for observations of the bulge (best visible in the Southern Hemisphere), so we really hope to work on this.
Hydrogen in the universe
Another issue we hope to make headway on is how much hydrogen there is in the universe, both right now and in earlier times in galaxies much, much farther away. And how that hydrogen is distributed: Is it mostly in small galaxies in the early universe, for instance?
We're now devising observation strategies and describing our plans so we can get teams and collaborations going early, before MeerKAT gets built. In two weeks, there is a big meeting here in Cape Town about the Square Kilometre Array (SKA). [MeerKAT is part of an effort to demonstrate the expertise needed to take on the larger SKA project.] So we plan to show our ideas during that and talk to people about collaborations.
It's not the most spectacular stage of a new project. Basically we're drumming up a policy document, but if we have a good one, and put together good teams, then it pays off in the long run.

Happy birthday to a grand old telescope

Daniel Pendick — Fri, 12 Dec 2008 16:57:00 GMT

California’s Mount Wilson Observatory (MWO) is celebrating the centennial of its famous 60-inch reflecting telescope. Upon its completion in 1908, the “60-inch,” as astronomers call it, was the largest telescope in the world. Pioneer astronomer George Ellery Hale commissioned the project under the auspices of the Carnegie Institution of Washington. The 22-ton behemoth saw first light December 13, 1908, and is considered the grandparent of all modern research telescopes.

Harold McAlister, MWO’s current director, took time to talk to us about the 60-inch telescope’s place in astronomical history and its current scientific activities.

Pendick: What was the first thing an astronomer looked at through the 60-inch telescope?

McAlister: So far, this question has stumped me and several of my colleagues knowledgeable about 60-inch history. MWO Superintendent Dave Jurasevich pointed out that Saturn was in the sky on the evening of December 13 when “first light” was obtained, and it seems inconceivable that it wasn't observed.

Pendick: Could you give us a very bare-bones overview of the effect the 60-inch had on astronomy in its day?

McAlister: The 60-inch was a turning point in telescope technology, launching all subsequent glass-based and precision-controlled telescopes. Even the dome was revolutionary with its attention to heat management and seeing preservation through its double-walled construction.

The telescope had an early and tremendous impact on astronomy through the discovery by Harlow Shapley that the Sun was well away from the galactic center — contrary to the then-conventional wisdom — and, on top of that, the galaxy was huge. This was a sort of ultimate conclusion of the Copernican Revolution, although Shapley believed that the Milky Way dominated the universe.

The first inkling that he was wrong also came from the 60-inch, which produced spectra of the Andromeda Nebula that resemble those of the Sun. This suggested that this "nebula" is composed of stars and not just gas.

Photographs of nebulae showed starlike "condensations," and the 60-inch found evidence of reddening through interstellar absorption from distant nebulae. The conversion of these objects to "galaxies" had to await Hubble and the 100-inch telescope, but the 60-inch paved the way for that ultimate revolution that showed the universe is a vast assemblage of galaxies.

Pendick: What are MWO’s major scientific activities nowadays?

McAlister: Mount Wilson continues a very active science role with daily observations of the Sun’s magnetic and sunspot properties being carried out at the 150-foot Tower Telescope by a University of California, Los Angeles, group directed by Roger Ulrich.

Helioseismology is the focus of University of Southern California professor Edward Rhodes' activities at the 60-foot Tower.

Two interferometers are pursuing high-resolution studies of stars and their immediate environs. The first of these is the Berkeley Infrared Spatial Interferometer, led by professor Charles Townes, which is pursuing the shapes of evolved giants and supergiants and the circumstellar material surrounding them.

The second is my own project, Georgia State University's CHARA Array, which has the world's longest operational interferometric baselines and is active in a variety of areas dealing with fundamental stellar astrophysics. These projects receive funding from the National Science Foundation, NASA, and other federal agencies, and are continuing George Ellery Hale's tradition of 24/7 astronomy.

The 100-inch is available for scientific programs, and, although there are no active users at present, the telescope has supported several efforts from the Jet Propulsion Laboratory and the U.S. Naval Observatory during the last couple of years. The 60-inch is routinely rented to individuals and groups for an unrivaled viewing experience, and is the largest telescope in the world made exclusively available for public viewing. Links to each of these programs can be found at our web site, www.mtwilson.edu.

Arecibo — saved by the bell!

Daniel Pendick — Tue, 21 Oct 2008 16:39:00 GMT

For a couple of years, the giant Arecibo Observatory in Puerto Rico has been under threat of closure because of budget cuts proposed by the National Science Foundation. It appears the budget axe will not fall on Arecibo’s valley-spanning disk just yet. Here is some communication we just received from Emily Schoenfelder of Edelman Public Relations in Washington, D.C.:

“The future of the world’s largest single-dish radio telescope and site for some of our nation’s most important astronomical research has been given the green light by the Bush Administration.

“After a tireless effort led by Puerto Rico Governor Aníbal Acevedo-Vilá and Puerto Rico Federal Affairs Administration Executive Director Flavio Cumpiano, a bill allotting $2 million for the continued operations of Puerto Rico’s Arecibo Observatory has just received the signature of President Bush. The 2008 NASA Reauthorization Act assigns necessary funds to the Observatory under the “Near-Earth Object” (NEO) program.

“Since November 2006, the Arecibo Observatory has been in danger of closing following a recommendation made by the Division of Astronomical Sciences at the NSF for funding to be cut from $8 to $4 million by 2011. The observatory currently operates on a 24-hour-basis, providing logistical support to scientists from all over the world, and employs approximately 140 people. If the president had not approved the bill, the observatory would be forced to shut down, putting important research and monitoring and valuable jobs in jeopardy.

“The Arecibo Observatory is important for the NASA exploratory program and Puerto Rico’s continued advancement. I wanted to share this latest news item with you and provide myself as a resource should you need additional information on the Observatory.”

See my earlier blog on this issue for details: Arecibo Telescope fights for the right to hunt killer asteroids

Additional Astronomy.com Arecibo news stories:

"First near-Earth triple asteroid found" (February 14, 2008)
"Life-forming amino acids found" (January 25, 2008)
"Volunteers needed to process data" (January 3, 2008)
"Radar echoes map asteroids" (May 20, 2004)