Technology Archives

May 27, 2011December 24, 2015 by VirtualAstro

Beginner’s Guide to Astronomy – Refractor Telescopes

If you ask someone to describe or draw a telescope, nine times out of ten it will be a refractor.

The refractor telescope is quite possibly the most common or easily recognized telescope. It is a very simple design, which has been around for hundreds of years.

The history of the refractor is that it was first invented in the Netherlands in 1608, and is credited to 3 individuals; Hans Lippershey, Zacharias Janssen – spectacle-makers and Jacob Metius.

In 1609 Galileo Galilei heard about the refracting telescope and made his own design, publically announcing his invention and further developing it through extensive experimentation. Galileo’s friend Johannes Kepler further experimented with the design, introducing convex lenses at both ends, improving the operation of the telescope.

Many advances were made and the refracting telescope became the primary instrument for astronomical observations, but there was one problem; they were huge and some were many tens of feet long!

But now, after more than 400 years and — luckily — through advances in know-how and technology, the refractor has become much more powerful and compact than some of the behemoths in the early days.

Refractors or refracting telescopes employ a simple optical system comprising of a hollow tube with a large primary or “objective lens” at one end, which refracts light collected by the objective lens and bends light rays to make them converge at a focal point.

Light waves which enter at an angle converge on the focal plane. It is the combination of both which form an image that is further refracted and magnified by a secondary lens which is actually the eyepiece. Different eyepieces give different magnifications.

The larger the size of the objective or primary lens = more light gathered. So a 6 inch refractor gathers more light than a 2 inch one. This means more detail can be seen.

There are two main types of refractor telescopes: “Chromatic” – entry level and upwards with 2 lens elements and “Apochromatic” – premium, advanced and expert level telescopes with 3 or more very high quality lens elements with exotic mixes of materials.

Chromatic refractor telescopes are particularly good for observing bright objects such as the moon, planets and resolving things like double stars, but many astronomers who image deep sky and other objects use very high quality apochromatic refractors, due to their superior optics.

Refractor telescopes are very low maintenance due to being a sealed system and it is a simple case of setup and enjoy, without the fiddling lengthy setup times you may get with other telescopes.

Refractors give clean and crisp views due to the sealed nature, unlike other telescopes like Newtonians which are subject to cooling and air turbulence issues.

Due to their small size they are very portable and can also be used for terrestrial observations the same as binoculars, which are basically two refractors bolted together.

April 29, 2011April 26, 2016 by VirtualAstro

Last & Best Chances to See NanoSail-D

Nanosail-D Pass Credit: Vesa Vauhkonen, Spaceweather.com

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Over the next few weeks, skywatchers will have excellent viewing opportunities for the NanoSail-D solar sail.

The satellite is coming to the end of its 95-day mission to test the viability of de-orbiting decommissioned satellites or space debris. NanoSail-D is now de-orbiting and slowly losing altitude in the Earths thin upper atmosphere.

As the satellite descends, viewing opportunities will improve.

To see NanoSail-D pass over, you will need to know exactly when it will be visible from your location. To do this, go to Heavens-above.com or Spaceweather.com where star charts with times and pass details will be displayed after you enter your observing site.

Once you know the time and location in the sky of the pass of the satellite, make sure you are able to get a good view of the part of the sky where the satellite due to appear. Give yourself plenty of time, go outside and get ready. I always set a 30 second reminder on my watch or cell phone, so I don’t have to fumble around or guess the time.

To enjoy the NanoSail-D passes:

• Make sure you know the right place in the sky and the time of the pass, by checking on the web.
• Make sure you will be able to get a clear view of it from your viewing location.
• Set an alarm or get ready for the pass as it only lasts a few seconds.
• NASA expects NanoSail-D to stay in orbit through May 2011.
• If you are an astrophotographer, don’t forget, NASA and SpaceWeather.com are having an imaging contest of NanoSail-D. Find out more here.
• Most of all, get your friends and family outside with you to watch NanoSail-D and enjoy!

Artist concept of Nanosail-D in Earth orbit. Credit: NASA

April 16, 2011December 24, 2015 by VirtualAstro

Telescope Eyepieces: The Weakest Link

Do you have a new telescope, or are you considering buying a new one? Hopefully, you have chosen a telescope with the best specifications for your budget, but before you can truly get the best out of your wonderful new window on the cosmos, you need to have something even more important than the scope – Eyepieces!

A lot of people new to astronomy, or new to buying astronomy equipment tend to concentrate on telescopes and unfortunately overlook eyepieces, settling for the basic set of 2 or 3 that come with the new telescope.

Eyepieces are probably the most important part of your observing equipment, as they are at the heart of your setup and can make your observing experience fantastic or disastrous, or make an average telescope great or an excellent telescope bad.

The Basics

Eyepieces are the part you look through and are responsible for magnification of the objects you see through the telescope. They come in many different magnifications and types, but it’s not rocket science. You will soon learn what eyepieces work well for seeing different astronomical objects.

Telescope eyepieces are designed to fit into the focuser of the telescope. Depending on your telescope, they come in two sizes 1.25” or 2” and there is .965” which is an older size and pretty much obsolete, unless you have an old telescope. Most telescopes can be fitted with adapters so both eyepiece sizes can be used.

Magnification

The magnifying power of any eyepiece is a simple equation expressed in millimetres: Divide the focal length of the telescope by the focal length of the eyepiece and your answer is the amount of magnification. Long focal length eyepieces such as 32mm and 25mm are lower magnification, while lower numbers like 10mm and 5mm are magnifying powerhouses.

It is always good practice to start observing an object with a lower power eyepiece such as a 40mm and gradually build up to higher powered eyepieces such as 10mm or lower. The reason for this is the telescope, human eye, seeing conditions and object being observed are all variable. Starting off with a high power such as 4.7mm may be a struggle.

Fainter objects such as nebula and galaxies are usually seen better with lower powers and you can really ramp up the power with bright objects like the moon.

Below are rough guides and are dependent on the telescope you use:

2mm-4.9mm Eyepieces: These are very high magnification and very difficult to use unless seeing conditions are perfect and the object observed is very bright, like the moon.

5mm – 6.9mm Eyepieces: These are good on bright objects such as the moon and bright planets, but are still very high power and work best with steady seeing conditions.

7mm – 9.9mm Eyepieces: These are very comfortable high magnification eyepieces and are excellent for observing brighter objects, a must for any eyepiece collection.

10mm – 13.9mm Eyepieces: These work well for all objects including brighter nebula and galaxies a good mid/high range magnification.

14mm – 17.9mm Eyepieces: These are a great mid range magnification and will help resolve globular clusters, galaxy details and planetary nebulae.

18mm – 24.9mm Eyepieces: These will work nicely to show wide field and extended objects, great mid-range magnification for objects like galaxy clusters and large open clusters.

25mm – 30.9mm Eyepieces: These are wider field eyepieces for large nebula and open clusters. A good finder eyepiece for locating objects before moving to higher powers.

31mm – 40mm Eyepieces: These are excellent for extended views and large star fields and make excellent finder eyepieces before moving to higher powers.

Eye Relief

Eye relief is the distance from the last surface of an eyepiece at which the eye can obtain the full viewing angle. If a viewer’s eye is outside this distance, a reduced field of view will be obtained and viewing the image through the eyepiece can be difficult. Generally longer eye relief is preferred.

Apparent Field of View

This is the apparent size of the image in the eyepiece and can range from about 35 to 100 degrees. Larger fields of view are more desired.

Types of Eyepiece

There are many different eyepiece types, some old and now obsolete, some simple and some advanced.

The different types of eyepiece are purely governed by the configuration of the glass and lenses inside the eyepiece. Some giving exceptional eye relief, wide fields of view, colour correction etc.

Some different brands of eyepiece include: Huygens, Ramsden, Kellner, Plössl, Orthoscopic and Kellner.

The most common and popular eyepiece type is the Plössl due to its good all round performance, good eye relief, approximate 50 degree field of view, pinpoint sharpness and good contrast. Plössl eyepieces are made by many manufacturers now, but there are excellent examples from manufacturers such as Meade and Televue.

Finally we have exotic eyepieces such as Super Wide and Ultra Wide which are usually 2” eyepieces, with higher powers up to around 4.7mm at 1.25” and are usually in the domain of the large Dobsonian or Newtonian telescope user, but are just at home on smaller telescopes such as refractors or Cassegrains.

These eyepieces sport amazing eye relief and huge “port hole” 80 – 100 degree views with fully loaded premium optics, which are very forgiving on telescopes with optical aberrations and other problems. They can make average or poor telescopes great, but there is a cost; an example of which is my 14mm Ultra Wide which cost £500 ($800) just for one eyepiece and I have a full set! Combined, my eyepieces are worth much, much more than the telescopes they are used on, but it’s worth it!

Eyepieces are the most important part of your observing equipment, choose them and use them well, which will help you enjoy observing through your telescope.

April 14, 2011December 24, 2015 by Nancy Atkinson

Cast Your Vote for Student “Spirit of Innovation” Awards

The Spirit of Innovation Award honors the memory of Pete Conrad

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The Spirit of Innovation Awards is a wonderful competition that challenges teams of high school students to create innovative products using science, technology, and entrepreneurship to solve 21st century, real-world problems. Right now, the student teams are battling for top pick this week as public voting opens in the Conrad Foundation (named in memory of Apollo astronaut Pete Conrad)Spirit of Innovation People’s Choice Awards, so check out the various teams and cast your vote. But do it now: public voting is runs only through April 17.

“Science and technology studies improve life around the globe, and expand our reach off of it,” said Pete Worden, Director of NASA Ames Research Center. “The People’s Choice Awards is an opportunity for the public to engage with student innovators demonstrating fresh and exciting developments in these fields. It gives everybody the chance to participate in a program that benefits our future.”

Conrad was commander of Apollo 12 and the third man to walk on the Moon. He had a learning disability, but went on to earn a scholarship to Princeton and lead a mission to the Moon.

This year’s People’s Choice champion will be announced Sunday, May 1 during the closing ceremonies of the 2011 Innovation Summit at NASA’s Ames Research Center. The Summit, April 28 – May 1st, is the culmination of the Spirit of Innovation Awards as the student teams present their products to entrepreneurs, scientists, and industry professionals, and compete for $5,000 Next Step Grants. The People’s Choice votes will be incorporated as 10 percent of the final judging score for these scholarships.

Last year, Team AM Rocks and its Solar Flare Nutrition Bar took home the People’s Choice Award winning title. This year the teams that garner the most People’s Choice votes in each of the challenge
categories -aerospace exploration, clean energy and cyber security -will be awarded $250. Meet this year’s teams, explore the innovations, and cast your vote for favorite, at this link.

Find out more about the Conrad Foundation here.

April 6, 2011January 18, 2016 by Jason Rhian

Coalition for Space Exploration Tasks us to “Think Outside the Circle”

The aerospace industry is typically filled with engineers, scientists and pilots. Hardly the segment of the population that is subject to expounding on the virtues of their trade in prose or through some other format. That said, every once and a while, a campaign, image or video comes along that simply nails what the men and women of the industry have been trying to say. Continue reading “Coalition for Space Exploration Tasks us to “Think Outside the Circle””

March 31, 2011April 26, 2016 by Nancy Atkinson

What Will Airplanes of the Future Look Like?

Artist concept of a futuristic 'flying wing' airplane. Credit: DLR

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Will aircraft of the future look something like this? Project NACRE (New Aircraft Concepts Research) has this wide-body aircraft in mind for future flyers, designed for long-haul flights and able to accommodate up to 750 passengers. Measuring 65 meters long, 19 meters high with a wingspan of nearly 100 meters, the maximum take-off weight of the simulated flying wing is roughly 700 tons. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has been performing flight tests to simulate and study the flight characteristics of large ‘flying wing’ configurations to prepare for future aircraft designs, using special airplane called ATTAS (Advanced Technologies Testing Aircraft System) research aircraft that has special software and hardware that can mimic the flight characteristics and performance of an entirely different aircraft.

What are some other future airplane concepts?

Airbus has this concept in mind – called a fantasy plane – that could be more fuel efficient because of its long, curled wings, a U-shaped tail, and a lightweight body. This could be the way planes look in 2030, Airbus says, and will have advanced interior systems, and be much quieter than current aircraft.

Boeing Icon II concept design. Credit: NASA/Boeing

This supersonic aircraft concept by Boeing is nicknamed Icon II has V-tails and upper surface engines, and can carry 120 passengers in a two-class, single-aisle interior, and can cruise at Mach 1.6 to Mach 1.8 with a range of about 5,000 nautical miles.

Boeing's SUGAR Volt will use considerably less fuel, reduce noise and take off from short distances. Credit: Boeing

Another concept from Boeing is the SUGAR Volt – which includes an electric battery gas turbine hybrid propulsion system – can reduce fuel burn by more than 70 percent and total energy use by 55 percent. This fuel burn reduction and the “greening” of the electrical power grid can greatly reduce emissions of life cycle carbon dioxide and nitrous oxide. Hybrid electric propulsion also has the potential to shorten takeoff distance and reduce noise.

Airplane or flying fish? This is one is called Smartfish.

This one is called the SmartFish, and utilizes a “lifting body” design, which means that the entire aircraft works to provide lift, rather than just the wings. The concept for this plane is a slender shape and composite material construction, which means less drag, and thus less thrust required for flight. The wing and fuselage form one integrated, futuristic-looking design. This plane can fly without slats, flaps, or spoilers, meaning increased fuel efficiency. See more on the SmartFish website.

Those are just a few concepts being tested and designed for the future of flight. You can read more about NASA’s work on the future of aeronautics here.

March 30, 2011December 24, 2015 by Anne Minard

New Technique Separates the Modest Red Giants From the … Giant Red Giants

Based on results from the first year of the Kepler mission, researchers have learned a way to distinguish two different groups of red giant stars: the giants, and the truly giant giants. The findings appear this week in Nature.

Red giants, having exhausted the supply of hydrogen in their cores, burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Until now, the very different stages looked roughly the same.

Lead author Timothy Bedding, from the University of Sydney in Australia, and his colleagues used high-precision photometry obtained by the Kepler spacecraft over
more than a year to measure oscillations in several hundred red giants.

Using a technique called asteroseismology, the researchers were able to place the stars into two clear groups, “allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly 50 seconds) and those that are also burning helium (period spacing 100 to 300 seconds),” they write. The latter population lend to the star an oscillation pattern dominated by gravity-mode period spacings.

In a related News and Views article, Travis Metcalfe of the Boulder, Colo.-based National Center for Atmospheric Research explains that like the sun, “the surface of a red giant seems to boil as convection brings heat up from the interior and radiates it into the coldness of outer space. These turbulent motions act like continuous starquakes, creating sound waves that travel down through the interior and back to the surface.” Some of the sounds, he writes, have just the right tone — a million times lower than what people can hear — to set up standing waves known as oscillations that cause the entire star to change its brightness regularly over hours and days, depending on its size. Asteroseismology is a method to measure those oscillations.

Metcalfe goes on to explain that a red giant’s life story depends not only on its age but also on its mass, with stars smaller than about twice the mass of the sun undergoing a sudden ignition called a helium flash.

“In more massive stars, the transition to helium core burning is gradual, so the stars exhibit a wider range of core sizes and never experience a helium flash. Bedding and colleagues show how these two populations can be distinguished observationally using their oscillation modes, providing new data to validate a previously untested prediction of stellar evolution theory,” he writes.

The study authors conclude that their new measurement of gravity-mode period spacings “is an extremely reliable parameter for distinguishing between stars in these two evolutionary stages, which are known to have very different core densities but are otherwise very similar in their fundamental properties (mass, luminosity and radius). We note that other asteroseismic observables, such as the small p-mode separations, are not able to do this.”

Source: Nature

March 23, 2011December 24, 2015 by Anne Minard

Probing the Moho Boundary – Earth’s Own Unexplored Frontier

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The boundary where Earth’s crust gives way to the unexplored mantle was first detected in 1909, because of a change in the travel of seismic waves. Named the Moho boundary for Andrija Mohorovicic, who listened to those seismic waves, the crust-mantle boundary is a frontier that remains elusive and compelling — harboring tantalizing clues as to the story of Earth’s formation — even as our technologies push into the outer reaches of the solar system and beyond.

The first serious attempts to probe the Moho boundary ran aground in the late 1950s. Now, technology already in use on a Japanese ship, combined with a United States digging program already under way, could finally yield success. Damon Teagle and Benoît Ildefonse have written about the ongoing efforts for an article in the journal Nature, released today.

Teagle is at the University of Southampton’s National Oceanography Centre in the UK, and Ildefonse is at Université Montpellier in France. They are co-chief scientists on an expedition called the IODP Expedition 335, “to obtain for the first time a section of the lower oceanic crust — the material lying just above the mantle,” they write.

The IODP is using the U.S. ship JOIDES Resolution, pictured above, which will drill from April to June this year off the coast of Costa Rica.

“This site is in ocean crust that formed superfast — at more than 20 centimetres a year, much faster than any present day crust formation,” the co-authors write. “That makes the upper crust there much thinner than elsewhere, so it is possible to reach the lower portions without having to drill very deep. Three previous expeditions to Hole 1256D have drilled down to more than 1.5 kilometres below the sea floor, into the transition zone between dikes and gabbros.”

This spring they hope to push it another 400 meters, and recover gabbros from the lower crust, “which will be the deepest types of rock ever extracted from beneath the sea floor,” even though the deepest hole reached 2,111 meters under the eastern Pacific off of Colombia, they write.

Microphotograph of a mantle xenolith, sampled on Rapa Island in French Polynesia. The colourful minerals (seen here under the microscope in cross-polarized light, each grain is about 1 to 5mm large) are olivine, the main constituent of the upper mantle. Credit : Andréa Tommasi (CNRS, Géosciences Montpellier)

Teagle and Ildefonse note that some pieces of the mantle have been thrust up to Earth’s surface during tectonic mountain building, and ejected from volcanoes and sea floor dikes. Those samples have provided clues to the mantle’s composition, but they don’t reveal the variability of the mantle — and all of the samples have been altered by the processes that revealed them.

They say the IODP mission should help to settle many debates, including how crust is formed at mid-ocean ridges, how magma from the mantle is intruded into the lower crust, the geometry and vigor of how sea water can pull heat from the lower oceanic crust and the contribution of the lower crust to marine magnetic anomalies. The project will also provide “further impetus for, and confidence in, deep ocean crust drilling,” write Teagle and Ildefonse — but it will reach a depth far less than what will be needed to actually get at the Moho boundary. It occurs at least 30 kilometers (18 miles) under the continents but just 6 kilometers (3.7 miles) under the seas.

That’s where Chikyu comes in. Launched in 2002, “Chikyu is a giant ship, capable of carrying 10 kilometres of drilling pipes, and is equipped for riser drilling in 2.5 kilometres of water,” the authors write. Although Chikyu wouldn’t yet be able to go the full distance, its design is advanced enough to be the launching pad for such efforts:

“The vessel has a riser system: an outer pipe surrounds the drill string — the steel pipe through which cores are recovered,” the co-authors write. “The drilling mud and cuttings are returned up to the vessel in the space between the two pipes. This helps to recycle the drilling mud, control its physical properties and the pressure within the drill hole and helps to stabilize the borehole walls.”

Teagle and Ildefonse say the ideal drilling program to reach the mantle boundary will happen in one of three places — off the coasts of Hawaii, Baja California and Costa Rica — where the water is the most shallow, over the coldest possible crust. Wherever and however it happens, they write, it will be worth doing:

“Drilling to the mantle is the most challenging endeavour in the history of Earth science. It will provide a legacy of fundamental scientific knowledge, and inspiration and training for the next generation of geoscientists, engineers and technologists.”

Source: Nature. See also the websites for Chikyu and JOIDES.

March 23, 2011April 26, 2016 by Nancy Atkinson

Iran Claims They’ve Built a Flying Saucer

The Zohal (lower right). Credit: Fars News Agency

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Iran’s Fars News Agency revealed that the country has built an unmanned flying saucer, named “Zohal” (Saturn in Persian) which will be used for various missions including aerial imaging. UPDATE: thanks to reader Robert McCelland, we now have an actual picture of the Zohal instead of the hoaky flying saucer image that was included in the Fars article (see below). It is not really all that big — more like a remote controlled toy helicopter — but reportedly the Zohal is equipped with an auto-pilot system, GPS and two separate imaging systems with full HD 10 mega-pixel picture quality and is able to take and send images simultaneously. It was unveiled in a ceremony attended by Supreme Leader of the Islamic Revolution Ayatollah Seyed Ali Khamenei at an exhibition of strategic technologies.

No detailed specifications were supplied such as exact size and flight capabilities, (except that it can fly vertically) but the report said it could fly both indoors and outside.

The craft was designed and developed jointly by Farnas Aerospace Company and Iranian Aviation and Space Industries Association (IASIA).

The original image on the Fars site:

This image accompanied a news article in Iran about the country's own flying saucer.

March 22, 2011December 24, 2015 by VirtualAstro

Why are Dobsonian Telescopes a Favorite Among Amateur Astronomers?

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Welcome to the scary and expensive world of buying your first, or replacing your old telescope!

I am asked all the time “What telescope should I buy” or “What telescope do I need to see X with?” Nine times out of ten, I recommend a Dobsonian Telescope.

So what is a Dobsonian telescope and why are they so good? Read on to find out why.

A Dobsonian is simplicity in itself; a simple set of optics on a simple mount. But don’t be fooled by this simplicity. Dobsonian telescopes are incredibly good and are great for amateurs and professional astronomers alike. They are also very economical compared to other telescopes.

The optical part of the telescope or OTA (Optical Tube Assembly) is the same as a Newtonian reflector telescope. It consists of a primary parabolic mirror and a flat secondary mirror in an open ended tube, with a focuser for an eyepiece set on the side. Light enters the tube, reflects off of the primary mirror at the base and is then focused onto the smaller flat secondary mirror and then finally, into an eyepiece. Simple!

The benefit of this type of optical arrangement is the telescopes light gathering ability. The more light gathered, equals more fainter objects to be seen. A light bucket!

Dobsonian/Newtonian telescopes have a big advantage over telescopes with lenses such as refractors and Cassegrain telescopes, as mirrors are a lot cheaper to make than lenses. Plus they can be a lot bigger!

Both Dobsonian and Newtonian telescopes are measured by the size of the diameter of their primary (big) mirror. Dobsonian sizes range from starter scopes of 6 inches up to 30 inches, but common sizes are 8 to 16 inches in diameter. They can be many times larger and less expensive to produce than scopes with lenses.

The second part of a Dobsonian telescope is the mount. As with the optical part the mount is just as simple, if not more so! A basic manual mount which supports the optical tube and can be manually moved by hand in the Altitude (up/down) and Azimuth (left/right) axis.

The mount is usually made from wood or metal with bearings and support for the two axis of movement. More so lately, some manufacturers have put GoTo systems with motors on some Dobsonian mounts. Personally I think it’s a bit over kill for a Dobsonian, as finding objects manually by star hopping or other manual methods helps you learn the sky better and can be fun.

Resist the urge to spend lots of money on small computerized scopes that will eventually never get used, as they can be too complicated or you may not see much through them apart from the brightest objects such as the Moon. A Dobsonian is a great all-around telescope, and are available in almost all telescope stores. Some people make their own homemade Dobsonian scopes too!

Due to the nature of the Alt-Az mount, Dobsonians are not suitable for long exposure astro imaging. For that you will need an equatorial mount, which will track the stars equatorially. You may have some success with webcam imaging with some of the GoTo Mounts though.

Skywatcher 10 inch Dobsonian Credit sherwoods-photo.com

Dobsonian telescopes are designed to be simple, easy to use and gather as much light as possible. Because of this robust simplicity, they are very economical and popular with astronomers of all levels of ability. My own and most favourite telescope is my Skywatcher 10-inch Dobsonian and I will probably be using it for many more years to come, as it is difficult to beat!

The name of the Dobsonian telescope comes from its creator John Dobson, who combined the simple design of the Newtonian telescope with the Alt-Azimuth mount. He originally made simple homemade scopes from household materials and ground mirrors out of the glass of old ship portholes.

John Dobson is the grandfather of Sidewalk Astronomy and co-founder of the San Francisco Sidewalk Astronomers.