October 18, 2017

Review: The Telescope by Geoff Anderson.

Few inventions are as near and dear to our hearts as that of the telescope. Before its invention, astronomy was scarcely better than its pseudo-science companion of astrology in its knowledge of predicting the universe as it truly is. In this week’s review, we’ll look at The Telescope by Geoff Anderson out from Princeton Press as it traces the history of this noble instrument, its origins, the theory of optics, and our present day understandings and the exciting realm of telescopes yet to come.

Out from Princeton University Press!

Out from Princeton University Press!

Think you know everything about telescopes? The Telescope will take you through designs from classical refractors to Coudè focus complexities. This would serve as a good 101 for anyone thinking of building or even purchasing a telescope, as a lot of the optical basics are discussed. You can even skip through chapters, and the author even suggests that you don’t have to struggle through chapters on interferometry (but of course we did!) unless you really want to.

Stately Flandrau Observatories' 14"... (Photo by Author).

The stately Flandrau Observatory 14-inch. (Photo by Author).

The study of how early astronomers actually functioned always personally fascinates me. We all know the discoveries of Galileo, but just how did he make those refractors in a renaissance era work shop? The absurdity of some of the focal lengths used was astounding; this was required to overcome the fringes on chromatic aberration until 2-element crown and flint objectives were perfected. And don’t forget, they had to handcraft eye-pieces, as well. Just how many modern day telescope makers do that?

The 7 1/2" Merz Refractor of Quito Observatory. (Photo by Author).

The 7 1/2″ Merz Refractor of Quito Observatory. (Photo by Author).

The evolution of site selection and observatory construction is also discussed; it’s a generally underappreciated fact that seeing and turbulence makes up about 90% of your ultimate astronomical success. Early telescope users were content to perch their tubes on the ledge of a study window. It’s only been in the last century or so that site selection prior to observatory construction has really matured. In the modern era, the effects of encroaching light pollution also has to be accounted for. Telescopes have gone from backyard curiosities to behemoths of national significance.

One mother of a scope; OWL. (Credit: ESO).

One Mother of a scope… OWL. (Credit: ESO).

The modern era of scopes is also traced, from the Hale and Keck telescopes to the Hubble Space Telescope, which is appropriately given its own chapter. The chapter “When Good Telescopes go Bad” is particularly illuminating, as it demonstrates the engineering challenges that seem to plague every great instrument. It’s been said that it’s never truly a great scientific or engineering breakthrough until someone has had a nervous breakdown, and building cutting edge telescopes is certainly a case in point.  The author also addresses the innovative methods the have been developed to squeeze as much information as possible out of every photon of light. Just think, we can know speed, direction, composition and more just from “tasting” starlight. This was first developed by the breakthrough of spectroscopy, and further refinements such as interferometry and adaptive optics have pushed the envelope even further. adaptive optics itself used to be classified, as it was used primarily to peek at Russian payloads in low-Earth orbit. Some of this technology is truly amazing; for example, did you know it’s possible to “record” a conversation in a room just by measuring via laser the vibrations imparted on the windows? To this effect, the Oval Office actually employs “shakers” on its outer panes, probably not much different than the vibrate mode on your cell phone.

An "backyard" scope that would have been the envy of many of the astronomers of yore... (Photo by Author).

A “backyard” scope that many earlier astronomers would have been envious of… (Photo by Author).

A look at the key discoveries of the telescope and some of the more bizarre and unusual telescopes is also given treatment; two of our favorite are the use of liquid metal (mercury in a precisely rotated dish!) telescopes, and of course, the Laser Interferometry Gravitational wave Observatory, a “telescope” used to hunt for gravity waves.

And that’s just the beginning. The future of telescopes will see the James Webb Space Telescope, mega observatories such as the Thirty Meter Telescope (TMT) and the 100-meter OverWhelmingly large telescope (OWL) and perhaps even more exotic arrays such as the Terrestrial Planet Finder or a large crater-based instrument on the Lunar far-side.

Do give the Telescope a look if you are thinking of buying, building, or just have a passion for these grand old instruments. Telescopes represent the cutting edge of human technology, and never fail to inspire. And as astronomers, observatories are the closest thing to a cathedral to the stars that we possess!

A modern day wonder! (Photo by Author).

A modern day marvel! (Photo by Author).

26.10.09:Seeing Starspots.

We know more about our Sun than any other star because it gives us the opportunity to study solar activity up close. But just how normal is it? Recently, astronomers have been able to spy activity on other suns, teasing the data out of exoplanet transits. These are planets that happen to cross the tiny visible face of their parent star as seen from our line of sight and thus exhibit a tiny but measurable dip in their apparent brightness. Earlier this year, a team at the Hamburg Observatory has been refining this technique by monitoring the star Corot-2a. A younger Sun-like star, Corot-2a spins once every 4.5 earth days and possesses a transiting “hot Jupiter” which orbits once every 1.74 days. Examining a statistical analysis of the light curve as seen by the European Space Agencies’ (ESA) prolific Corot space observatory has yielded “notches” in the smooth curve, a tell-tale sign of “starspot” activity. This was conducted over 80 successive transits. The goal is to begin puzzling together a “butterfly diagram” for alien suns, much like the familiar 11 year cycle diagram yielded by Sporer’s Law for our own Sun. Doubtless, other suns follow different cycles, and this data will add to our understanding of stellar evolution. This will also answer such questions about our own Sun, such as; why do sunspots never form above a particular latitude? Are there larger interwoven cycles? And just what was our Sun like in its juvenile days?



23.10.09:Fermi Pegs Gamma-Ray Pulsars.

NASA’s Large Area Telescope aboard the orbiting Fermi gamma-ray observatory continues to turn out some amazing science, picking up where Compton left off in 2002 as it surveys the gamma-ray sky. Of particular interest are gamma-rays emitted from pulsars. Pulsars are the swiftly rotating remnants of massive stars that have gone supernova, leaving a superdense core in their wake. These are sometimes called “neutron stars” because the matter comprising them is packed so tightly the individual nuclei are literally stacked end to end, making a spoonful weigh as much as a mountain! After all, most ordinary matter is made of….nothing. A neutron star can be thought of as a large, singular atomic nucleus, again weird stuff. Most of the 1,800 pulsars thus detected are because of their copious radio emissions beaming from their poles. Thus, we have to be in the line of sight before we see their blinking radio pulsations. Enter Fermi, which has thus far spotted 16 new pulsars via their gamma-ray emissions alone. This promises to aid in identifying pulsars whose poles aren’t tipped to our line of sight, which are probably in the majority. But even the gamma-ray sky is relatively dim; for example, the Vela pulsar is one of the brightest in the sky, and it emits a mere 1 gamma-ray photon every 2 minutes! Initially dubbed “Little Green Men” (LGMs!) during their discovery in the 1960′s, pulsars were soon naturally explained, but still continue to amaze. Watch this space and the Fermi mission for news from the high energy end of the spectrum!

02.10.09: A Small Observatory Helps with a Big Discovery.

When it comes to cutting edge astronomy, many think of lofty mountaintop behemoths, such as Keck, or the orbiting Hubble Space Telescope. But how many of us think of… Gainesville, Florida? This article caught my eye this morning because its literally right in our backyard here at Astroguyz HQ in Hudson, Florida. As any would-be Floridian astronomer knows, the Sunshine State is not an optimal environment for astronomy, as humid, damp, East Coast conditions predominate. But that didn’t stop astronomers at the University of Florida in Gainesville from using the Rosemary Hill Observatory in nearby Bronson to help with observations of a transiting exoplanet; HD 80606b. 200 light-years distant, this hot-Jupiter is in an extremely eccentric orbit and was only recently realized to be a transiter, i.e. to occasionally pass in front of its host star as seen from Earth. Astronomers, however, were faced with a problem; the next transit was due occur June 4th of this year, when HD 80606b would be low in the twilight sky. This meant that observations of the eclipse could only occur over a short span from any given longitude. Enter U of F astronomers Ford, Reyes and Colon, who realized that Rosemary Hill might just be positioned to catch such an event. Located, as is most of Florida, at a scant 140 feet above sea level, Rosemary Hill may just qualify as the “lowest” observatory in the world. It sports 30” and 18” reflecting telescope(s), which are primarily used for education and training, as the U of F astronomers tend to travel to the “big guns” in the Canary Islands for “serious” research. The night of the 4th, however, Rosemary Hill showed its stuff; as a participating observatory in Massachusetts was clouded out, leaving the Gainesville astronomers as key to gathering data at their respective longitude. Colon noted that the experience of actually guiding the telescope and monitoring the star during transit was “definitely unique” and different from the remote observing now prevalent at larger observatories… the data gathered will go far towards understanding this bizarre exoplanet and its 111 day orbit. And the moral of the story is…every telescope can contribute, even your home town observatory!

Event of the Week: 29.06.09: The Deepening Solar Minimum.

Something mildly bizarre is happening on our nearest star, the Sun. Or should we say, a lack there of… This weeks astro-event is a sort of non-event, but one of the big mysteries of 2009; where exactly are the sunspots? Turning that newly constructed white-light filter we built last week on our mild-mannered star shows a definite lack of activity in the solar photosphere. This isn’t entirely abnormal, as the Sun is just coming off of a solar minimum that occurs every 11 years. What is unusual is the length of this minimum; we’ve had over 600+ spotless days since 2004, a quarter of which have been in 2009 alone. A typical minimum consists of an average of 485 days. You have to go way back to 1913 to find such comparable a lull! Two tiny sunspots appeared last week, which prompted the discussion as to whether the latent solar cycle #24 is finally amping up or not. Both spots belong to the new cycle, their reversed polarity giving them away. Using the technique of helioseismology, Frank Hill and Rachel Howe at Tucson’s National Solar Observatory have discovered that the Sun’s internal dynamo isn’t dead, just sleeping. They predict that the subsurface tachocline should begin intersecting the surface at the junction of 22 degrees latitude by the end of 2009, and activity should resume. It’ll be a wait and see mystery that will only deepen if the spots don’t return to roost; and does this portend a stronger than usual maximum around the solar bend? Stay tuned!

This week’s astro-term of the week is Sporer’s Law. First worked out by astronomer Gustav Sporer, this law simply states that sunspots form at higher latitudes at the beginning of a solar cycle, and then gradually progress downward to lower latitudes in both hemispheres as the cycle progresses. We never see spots above 45 degrees of latitude, and astronomers aren’t quite sure why. The link between the solar cycle and the climate isn’t yet fully understood. Could a spotless Sun mimic or mask the effects of global warming? Both Earth and space bound telescopes are keeping a constant watch on our Sun. Cries of another Maunder minimum, a time from 1645 to 1715 that was marked by harsh winters and almost no sunspots were seen, may be a bit premature… cycle #24 were art thou?

Constructing the Very Small Optical Observatory.

Ahhh… eternal the lure of having ones’ own observatory. Batman has the Bat-cave, Superman has his Fortress of Solitude, and sooner or later, every astronomer heeds the siren song of having a place he and his mammoth telescope can call home. The perks are many fold; an observatory means you spend more time observing, not lugging, setting up, aligning, watching the clouds roll in, and packing it all back in. This week, I’m going to tell you the tale of how I built my own modest shrine to the stars, cheaply and quickly.

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Astro-Event of the Week: 03.30.09: 100 Hours of Astronomy!

This week’s shout-out is not an event in the skies above, but a global happening right here on the good ol’ planet Earth. On April 2nd thru the 5th, the International Year of Astronomy (IYA) 2009 culminates with an unprecedented global event: 100 Hours of non-stop Astronomy!

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Your own Personal Astronomer: Tucson’s Flandrau Observatory.

Looking for an affordable, innovative date? One of the kept secrets in the deep Arizona desert is absolutely free; I give you a night of star gazing and cosmic conundrums at the Flandrau Observatory, adjoining with the Science Center of the same name. Located on the University of Arizona campus in Tucson, Arizona, the dome boasts a 16-inch Schmidt-Cassegrain reflector and a knowledgeable telescope operator to go with it.  How do I know this? Because I myself was one such operator during the heady days of 2006, and could easily state that the experience was one of the most rewarding of my life.

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