Astronomy & Science

Visit Iceland and Shoot the Northern Lights!

Sky&Telescope -

Sky & Telescope's third annual trip to Iceland, this time accompanied by Equipment Editor Sean Walker, provides a fantastic opportunity to photograph the aurora borealis.

Once you’ve experienced a vivid display of the Northern Lights, the experience stays with you for the rest of your life. My first display came unexpectedly while I was amid the dark skies of the White Mountains in New Hampshire to shoot Comet Hale-Bopp. It was early on a March morning in 1997. Shortly after setting up and beginning my first exposures, I noticed tall, thin clouds to the north. I watched these light streaks for a minute or so, worrying that these clouds would ruin my photos if they moved down to the east. It wasn’t until they began to change shape and disappear as they entered the northeast of my sky, while more began sprouting up in the northwest, that I realized what these were — the Northern Lights!

iceland.is

Photographing the aurora in Iceland.
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The display lasted only about a half-hour, and at its most active point, I could just make out a slightly reddish tint to the lower portions of the rays. Even more fortunate was that I had all the equipment ready to take photos of the event. I fired off an entire roll of film, and managed to catch a few nice photos to relive the experience. I’ve seen a few other displays since that time, but the Northern Lights rarely dip down into the Lower 48 states. If you want a better chance of seeing them, you need to go where they occur most frequently.

This is why I’m very excited to help lead S&T’s third annual aurora trip to Iceland this October. Auroras occur within an oval up to 900 miles wide centered on Earth’s geomagnetic poles. Iceland, being within the Arctic Circle, always lies beneath or very near this ever-shifting oval, so we’ll have a front-row seat to most auroral displays, even when a strong geomagnetic storm isn’t in the forecast.

For reasons not yet understood, strong auroras happen more frequently around the equinoxes, making October a great time to look for them. We’ve scheduled our tour for a time when the Moon won’t interfere too much with our viewing. We've just passed solar maximum, the time of greatest solar activity in the Sun’s typically 11-year cycle, but exceptional auroras can still occur for years to come.

If you’re interested in photographing them yourself, you only need a camera with some manual features, a tripod, and some way to keep the shutter open. I’ll be on hand to help you take the best photos within your means of any auroral displays we see. Or you can just bask in the magical moment, and I’ll happily share my own results with the group.

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Skógafoss waterfall in Iceland.
iceland.is

During the day we’ll visit some iconic natural and cultural features of Iceland. See the itinerary for complete details.

Hope to see you in Reykjavík this fall!

Space is limited, so book now! For more tour information, contact Spears Travel. Ready to book the trip? Click here.

The post Visit Iceland and Shoot the Northern Lights! appeared first on Sky & Telescope.

Close-Up of Saturn’s Moon Hyperion

Sky&Telescope -

On May 31st, the Cassini spacecraft flew by Saturn’s funky moon Hyperion. The resulting images highlight the moon’s unusually pocked surface.

Hyperion

This image was taken with Cassini’s narrow-angle camera. Although Saturn’s other outer moons also have craters on their surfaces, Hyperion’s craters appear to be exceptionally deep. Astronomers have likened the moon’s appearance to a sponge or a wasp’s nest.
Credit: NASA / ESA

Hyperion is one of our solar system’s most intriguing objects. One reason is its unusually low density. Although it’s the largest of Saturn’s potato-shaped moons, with an average diameter of 270 km (170 miles, less than a tenth our Moon’s size), it has a density about half that of water. Due to this low density, and the high reflectivity of its craters’ sides, planetary geologists surmise that the moon is made largely of water ice.

Another interesting tidbit about Hyperion concerns its chaotic rotation. Most moons in the solar system rotate synchronously, which means that they always point the same side at their host planet. Our own Moon exhibits this behavior, which is why we can never see its farside from Earth. Hyperion, however, will face any of its sides toward Saturn at random. Planetary scientists recently discovered that Pluto’s moons Nix and Hydra are also rotating chaotically. Researchers are still searching for the cause of this rotation chaos.

Hyperion’s porous appearance is also mystifying. Although the sides of the moon’s craters are bright, the bottoms look very dark. Some astronomers argue that the color and depth could be due to waste left over by volatile elements (those elements with a low boiling point, such as carbon dioxide and methane) when they were heated and vaporized. The resulting darkly colored sediment would soak up additional heat from the Sun, continuing the vaporization process and thus deepening the craters even more.

However, others argue that Saturn and its moons are too far from the Sun to explain the necessary heating. Instead (or, maybe, also), Hyperion potentially formed from the rubble left behind by a large impact. The miscellaneous pieces of ice and rock debris stuck together but didn’t have enough gravity to compact themselves. The result would be a porous, low-density body.

Hyperion2

A close-up of Hyperion’s spongy surface. Note the bright crater edges and dark bottoms.
Credit: NASA / ESA

Cassini will continue to explore Saturn’s moons until 2017, when it will begin its final mission to fly in and out of Saturn’s ring system.

The post Close-Up of Saturn’s Moon Hyperion appeared first on Sky & Telescope.

Observing at the Diffraction Limit

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Observing at the Diffraction Limit

Laird Close (University of Arizona), MagAO's Principal Investigator, observes alpha Centauri A and B at the diffraction limit. The inset shows an image of the binary star system recorded with MagAO's visible-wavelength science camera. This photo was featured on NASA's Astronomy Picture of the Day.
Yuri Beletsky / Carnegie Observatories; inset: Jared Males

Even on the darkest, clearest night, turbulence in our atmosphere moves the air between us and outer space, bending and shifting starlight. Pretty as they are, those twinkling stars cause astronomers several problems, the main one being the loss of angular resolution.

Consider binary, or double, stars. Angular resolution is what enables us to separate a pair — if the stars orbit too closely, they will appear as one. Atmosphere-induced twinkling limits astronomical observations to a resolution of (roughly) 1 arcsecond, and amazingly, this is as true on a 10-cm (4-inch) backyard telescope as it is on the 10-meter (33-foot) Keck telescopes in Hawaii.

One way to avoid twinkling is to escape Earth’s atmosphere. The Hubble Space Telescope is “diffraction limited”­ — soaring above most of the atmosphere in low-Earth orbit, the telescope’s angular resolution is set by the ratio of the wavelength of light to the diameter of the primary mirror. Since the primary mirror is 2.4 meters across, Hubble can resolve two stars in visible light even if they are just 0.05 arcseconds apart -- a factor of 20 better than from the ground.

Now imagine for a moment what it would be like to look through Hubble with your eyes . . .

That becomes a possibility or Earthbound telescopes that use adaptive optics (AO), which measures the atmospheric turbulence and then bends a mirror to correct the bent path of the light rays. In other words, AO stops the stars from twinkling.

Magellan Telescopes

The twin Magellan telescopes, named Baade and Clay, each have mirrors 6.5 m in diameter. MagAO is mounted on Clay, on the right in this image, taken at Las Campanas Observatory in Chile.
Jared Males; inset: Google Maps

I work on one such system, called MagAO, which is mounted on the 6.5-meter Magellan Clay telescope at Las Campanas Observatory in Chile. Our system is special for a few reasons. To correct the turbulence, we use a thin mirror with 585 magnets glued to the back, which serves as the telescope’s secondary mirror We push and pull on the magnets 1,000 times a second to respond to and correct for atmospheric changes. Most AO systems built so far work only in the infrared. MagAO works at those wavelengths too, but it also corrects visible-light images. A special beam-splitting optic enables us to take visible and infrared images simultaneously. With such a large primary mirror, MagAO achieves resolution as good as 0.02 arcseconds at visible wavelengths —even better than Hubble.

Usually, AO systems feed into cameras, which take long-exposure pictures of the night sky. But just a few weeks ago, we got the opportunity to see the results with our own eyes. We were setting up for our current observing campaign, but our infrared science camera, Clio, wasn't quite ready to go. So for our first night, we instead mounted a simple eyepiece in Clio's place and replaced the special beam-splitter with a red filter that passes wavelengths longer than 685 nanometers.

We pointed the Clay telescope at the Alpha Centauri binary system and turned on the MagAO system. The difference was dramatic: we watched as each twinkling blob collapsed into a stable point of light. With our own eyes, we saw details as fine as 22 milliarcseconds across, even sharper than if we were using Hubble!

Sketch of Alpha Centauri

A sketch of what Alpha Centauri looked like through the eyepiece by Katie Morzinski, MagAO's Instrument Scientist. This was a lot of fun for us — professional astronomers almost never get to look through our telescopes with our own eyes.
Katie Morzinski

You can read more about our night of eyepiece observing at the MagAO team's blog. We are in the middle of a 6-week observing run, and we post a daily update. Follow along as we explore the universe at the limit of diffraction!

Jared Males is a NASA Sagan Fellow at the University of Arizona, where he studies exoplanets with direct imaging and adaptive optics.  He received his PhD from the University of Arizona in 2013, where he helped develop the Magellan AO system and its VisAO camera.

The post Observing at the Diffraction Limit appeared first on Sky & Telescope.

Litchfield Hill Amateur Astronomy Club

Sky&Telescope -

NAME

Litchfield Hill Amateur Astronomy Club

ADDRESS

155 Sycamore Drive
Torrington
Connecticut 06790 USA

CONTACT

Mark Croce

PHONE EMAIL

lhaacsec@gmail.com

URL

www.lhastro.org

NUMBER OF MEMBERS

25

OTHER INFORMATION

meets 2nd Friday each month. Monthly observing sessions at White Memorial Conservation Center in Litchfield as noted on website

The post Litchfield Hill Amateur Astronomy Club appeared first on Sky & Telescope.

Get Started Right with Your First Telescope

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Sky & Telescope's introductory videos walk you through all aspects of buying, using, and caring for your first telescope.

My wife is not thrilled with the fact that I own more than a dozen telescopes. They're in all shapes and sizes: from the 60-mm Japanese refractor given to me when I was 12 to the big Celestron 9¼-inch Go To Schmidt-Cass hat I use for more demanding observations.

Most of my collection, however, falls in the general category of "beginner scopes." Here's why: Over the decades I've been approached by countless newbies who just want to know how to make their scopes work properly. I sometimes realize that they haven't bothered to read the instructions — but more often it's that the manual is woefully incomplete or confusing (or both). Rare is the telescope that comes with user-friendly guidance for finding things in the sky and, critically, for taking care of the purchase so that it can truly last a lifetime.

If only there were simple, accurate how-to videos to guide the millions of people who buy their first telescope every yet. But there weren't. Last year, after spending a lot of time scouring YouTube, Vimeo, and other internet video collections, the editors of Sky & Telescope decided to produce our own. The result, described in more detail here, is a set of four videos that every newbie should have. The titles are self-explanatory: Buying Your First Telescope, A Guide To Using Your Telescope, Care and Cleaning of Your Telescope Optics, and Accessories for Your Telescope.

Kelly Beatty & Dean Regas

Kelly Beatty & Dean Regas show what to look for before — and after — buying your first telescope.
Sky & Telescope

My co-host for these videos is Dean Regas, an S&T contributing editor who works at Cincinnati Observatory and has become well known as the co-host of the popular PBS show Star Gazers. Before the cameras rolled, we carefully mapped out all the aspects of telescope ownership that first-time buyers (or even long-time owners) would need to know. We made them as complete as reasonably possible.

You can get this quartet of videos either as individual digital downloads (click on the links above) or buy them bundled on a DVD. In this season of "dads and grads," our Skywatching Series of telescope videos gives you a lot terrific information and tips that you just won't find anywhere else.

("Now," my wife says,"maybe you need a video on how to sell used telescopes.")

The post Get Started Right with Your First Telescope appeared first on Sky & Telescope.

Learn the Night Sky with Sky & Telescope’s Planisphere

Sky&Telescope -

Hawaiian night sky

The night sky above Mauna Kea observatories.
Sean Goebel

I have a confession to make: some professional astronomers (especially the high-energy kind) understand the night sky less than you do. As a professional astronomer, I took the opportunity to visit Mauna Kea during a conference in Hawaii, and I gazed up at stars that looked so close I could touch them. Next to me at the [astronomer’s way station], the tour bus’s driver asked me, “So, what constellations are we looking at here?” And I had no idea.

Part of it was that I’d never been under a sky so dark and so full of stars. I’d only glimpsed the Milky Way a few times before, and nothing had prepared me for the ridiculously clear skies atop the Big Island.

Sky & Telescope's planisphere

The 40°N sky chart

But the larger part of it is that as a professional astronomer, I rarely had cause to study the naked-eye sky. I was too busy analyzing X-rays collected by the space telescopes Chandra and XMM-Newton, pondering the accretion disks feeding supermassive black holes in very faraway quasars.

Those Hawaiian skies convinced me otherwise. It’s one thing to feel awed by the vastness of our cosmos (and studying gobbling supermassive black holes tends to bring that on too), but once I felt that awe in person, I started wanting to understand it, too, to feel a part of it. What that translates to is wanting to learn the names and patterns of the stars, the signposts and waymarks of the night sky.

And Sky & Telescope’s planisphere is the way to do that. The star wheel is simple to use yet eternally useful. Senior Editor Alan MacRobert explains our planisphere in this video (start at 3:00 for the planisphere walk-through), but really, as soon as the planisphere is in your hand, you’ll be enjoying a newfound mastery of the night sky.

If you’ve been hankering for this or any other get-started guide to astronomy, this is the weekend to buy: we’ve got a Friends & Family sale going on in our online store that’s put everything in our store at 40% off, now through Sunday!

Happy stargazing!

The post Learn the Night Sky with Sky & Telescope’s Planisphere appeared first on Sky & Telescope.

New Insights From Rosetta’s Comet Mission

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Rosetta continues to help astronomers better understand the way comets form and how they interact with the universe around them.

The European Space Agency’s (ESA) Rosetta mission to comet 67P/Churyumov–Gerasimenko (Chury), launched in 2004, has allowed astronomers to get the closest and most detailed look at a comet ever. Two recent studies, borne of Rosetta’s heaps of data, are particularly eye-opening, and offer clues about comet formation and the complicated chemistry at work above a comet’s surface.

How to Make a Comet

Have you ever wanted to see how a comet forms? Now you can! Based on topographic and structural data collected by Rosetta and other comet-related missions, Martin Jutzi (University of Bern) and Erik Asphaug (Arizona University) have created a 3D simulation of how bi-lobed comets form.

In the video, two balls of ice collide at bicycle speed, bounce off each other, and begin to rotate.

The Chury Comet

This composite is a mosaic comprising four individual NAVCAM images taken from 19 miles (31 kilometers) from the center of comet 67P/Churyumov-Gerasimenko on Nov. 20, 2014. Image credit: ESA/Rosetta/NAVCAM

Due to mutual gravity, the smaller one begins to lose momentum and is eventually pulled back toward the larger. About 14 hours later they collide again, and this time they stick together for good. The result is one bi-lobed comet. Approximately half of all the comets astronomers have observed so far are bi-lobed.

Jutzi and Asphaug argue that these types of low-velocity collisions were likely very common in the early solar system, before the Sun and planets were formed, when there weren’t any large objects around to whip smaller bodies into high-speed frenzies.

Electron and Photon Chaos

In addition to helping astronomers understand how comets might form, Rosetta has also revealed more about the chemistry behind what happens at a comet’s surface as it approaches the Sun.

When a comet gets within a certain distance of the Sun, ultraviolet (UV) photons bombard the comet’s surface, causing it to spew gaseous plumes of water and carbon dioxide molecules. These molecules then break up into their atomic parts (hydrogen, oxygen, carbon and nitrogen), surround the comet like a nebula (known as the coma), and emit UV light. Our Earth-orbiting telescopes have been able to detect this light, and the solar photons, but are too far away to observe the interaction at a detailed, atomic level.

Rosetta has allowed for a much closer look at this process during its orbit around the Chury comet. In an analysis of the craft’s data, Paul Feldman (Johns Hopkins University) and colleagues identified an additional culprit involved in this coma chaos: electrons.

Rosetta carries a special instrument onboard, a spectrograph dubbed Alice, that detects UV light and splits it into its individual color components. Since each color corresponds to an element, researchers can use the spectrograph to identify the composition of the object emitting the UV light. In Chury’s case, they were also able to map out exactly how the water and carbon dioxide molecules were ripped apart. This is how they discovered the electrons’ role.

First, photons from the Sun slam into the comet’s water and carbon dioxide molecules. The collisions cause these molecules to shoot out high-energy electrons, which in turn smash back into the original molecules, causing them to split into zillions of atomic bits. The result is a horde of free-floating hydrogen, oxygen, carbon, and nitrogen atoms that emit the UV light our Earth-orbiting telescopes have captured.

Astronomers are thrilled to be able to observe this chemical process in such detail, but Alice’s success is exciting for another reason. A second Alice instrument, aboard New Horizons, is on its way to explore Pluto and the Kuiper Belt. The spacecraft is scheduled for a Pluto flyby on July 14th, 2015, with its own Alice spectrograph ready to collect data just as valuable to scientists.

References:

Martin Jutzi and Erik Asphaug. “The Shape and Structure of Cometary Nuclei As a Result of Low-Velocity Accretion.” Science Express, May 28, 2015.

Paul Feldman et al. “Measurements of the Near-Nucleus Coma of Comet 67P/Churyumov-Gerasimenko with the Alice Far-Ultraviolet Spectrograph on Rosetta.” Astronomy & Astrophysics, June 1, 2015.

Relive Rosetta's long-awaited arrival at the comet it had chased for a decade before entering orbit — catch the full story in Sky & Telescope's August 2014 digital issue.

The post New Insights From Rosetta’s Comet Mission appeared first on Sky & Telescope.

Respuesta a: ¿Son responsables los famosos de la publicidad que hacen?

Ciencia Kanija -

Esta mañana, mientras hacía mi repaso habitual por las noticias publicadas en los medios que sigo, apareció un post que llamó mi atención especialmente. El amigo José Manuel López (@ScientiaBlog) escribía un post en su blog, absolutamente recomendable, por si no lo conocían, titulado ¿Son responsables los famosos de la publicidad que hacen?

Mi respuesta por twitter tras leer el post, en un alarde de prosa, fue:

@ScientiaJMLN Sí, claro que lo son.

— Ciencia Kanija (@CienciaKanija) June 5, 2015

A lo que obtuve una respuesta que me hizo recordar mis años de estudiante:

@CienciaKanija lee y argumenta en el blog…que pareces de Córdoba, — José M López Nicolás (@ScientiaJMLN) June 5, 2015

Traducción, “justifique su respuesta”. Y bueno, a eso voy.

Antes de nada, sugiero que se pongan en antecedentes leyendo el post original, que enlazo más arriba. En él, se lanzan dos preguntas:

¿Tienen responsabilidad los famosos en los productos que publicitan? ¿Se les puede culpar de que los alimentos o complementos alimenticios a los que ceden su imagen no cumplan lo que prometen y puedan confundir al consumidor?

En cierto modo, supongo que todos hemos asumido que la publicidad es mentira, lo cual no quita para que nos estén mintiendo descaradamente.

Power Balance D-Rose

Aquí tenemos a Derrick Rose, el fenomenal base de los Chicago Bulls, gran estrella de la NBA, anunciando la nunca suficientemente denostada Power Balance.

¿Es responsable el señor Rose de la publicidad de Power Balance? ¿Es responsable de que Power Balance fuese una tira de plástico con un holograma que no sirviera para mucho más que ganar un montón de dinero a sus creadores?

¿Por qué?

Pues porque está ofreciendo su imagen, y no sólo su imagen, sino todo un pack que lo acompaña. Es un deportista de élite vendiendo un producto que publicita un mejor rendimiento físico. El señor Rose, al aparecer publicitando este producto, explícitamente está dándole el visto bueno. “Yo, deportista de élite, uso este producto y funciona. ¡Cómpralo!”. Estás asociando no ya sólo tu imagen, sino tu propia marca personal, a un producto, y, con ello, avalándolo, generando ventas, y obteniendo un beneficio de las mismas en concepto de contrato de publicidad.

Cuando yo, humilde bloguero, recibo una oferta de publicidad para este espacio, tengo dos opciones. Decir a todo que sí, coger la pasta y correr, o tener un poco de decencia, informarme del producto que voy a publicitar y, una vez llego a una conclusión, promocionar o no el producto.

Ojo, no estoy hablando de que tengamos que ser expertos en todo. Estoy hablando de recabar información, de tener sentido crítico, de ser HONESTO, y, por qué no, de exigir una demostración de las bondades del producto.

Una señora vendiendo una crema antiarrugas no tiene por qué ser experta en bioquímica, ni estar al tanto de la normativa europea, podría simplemente decir: “Déjame que pruebe el producto durante un mes, si funciona como dices, te lo vendo”. Podríamos caer en el efecto placebo, en el amimefuncionismo, pero al menos sería un anuncio honesto de una persona que está vendiendo algo que considera realmente beneficioso.

No estamos hablando de una responsabilidad legal, ni siquiera de un conocimiento profundo de cada producto que se venda. Estamos hablando de responsabilidad moral. Y no sólo responsabilidad con aquellos compradores que han adquirido el producto porque tú lo estás vendiendo, sino incluso con tu propia marca.

¿Ven ustedes a Derrick Rose de la misma forma desde que han visto la publicidad de arriba? Posiblemente, sí, ya que asumen que ni se ha molestado en saber si funcionaba o no el plástico en cuestión, simplemente ha cobrado por poner la cara, sin embargo, en otros casos puede llevar al hundimiento de su imagen.

Puede ser que, cuando las cifras aumentan, la honestidad quede en un segundo plano. Que pienses que quizá no es tan importante, que no hace mal a nadie pero, en mi caso, no me gusta que aparezca mi nombre asociado a nada en lo que no crea.

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