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Carolyn Collins Petersen

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Hubble Measures Distances in the Cosmos

Thursday April 24, 2014

How Far Away is that Star... or Galaxy... or Cluster of Galaxies?

One of Hubble Space Telescope's most fascinating discoveries isn't necessarily a pretty picture. It's something quite profound: refining distance measurements of the universe. Yes, it sounds rather boring, but knowing the dimensions of the universe is an important part of understanding the universe itself.

Hubble measures cosmic distances.

To get to Hubble's contribution to measuring the universe, let's look at how astronomers measure distances. One way to do it is to bounce a laser off of a nearby object. Measure the time it takes for the laser beam to go from Point A to Point B, and back to Point A again. You know that light goes 186,252 miles (299,000 km) per second, and so it's an easy calculation to figure out how far it went in the time it took for the light to make the round-trip. NASA has done this many times with the Moon. There are reflectors on the lunar surface, placed so that astronomers can bounce lasers off them. Using this method, the average time it takes is 1.28 seconds.  This puts the Moon at an average distance of 238,900 miles.

That method works well for very close objects that have hard surfaces. But, when you want to measure distances to stars or galaxies, different methods have to be used.  The most reliable one for making astronomical distance measurements to faraway objects is to use straightforward geometry. Astronomers use the 186-million-mile diameter of Earth's orbit to construct a baseline of a triangle, much as a land surveyor would use. If a target star is close enough, it will appear to zigzag on the sky during the year as Earth moves through its orbit.

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Look Deep Into the Universe

Thursday April 17, 2014

See Galaxies!

What do you see if you look out at the universe? From Earth's surface, you see stars, planets, and galaxies. Of all these objects, galaxies are the most fascinating and evocative, but also tougher to spot in the sky than the others. Yes, there are a few naked-eye galaxies: the Andromeda Galaxy, and the Large and Small Magellanic Clouds. If you want to be complete, of course the Milky Way Galaxy is extremely easy to spot, but only because we're IN it. Most other galaxies are outside ours and they require magnification (binoculars and telescopes) if you want to see more than fuzzy blob of light. Astronomers have always seen many more galaxies with their larger research observatories, but nowadays, with the advent of advanced telescopes, such as Hubble Space Telescope, they're seeing a LOT more galaxies than they used to!

Image of galaxies

This image shows a galaxy cluster set against a backdrop of more distant galaxies. This is a remarkable cross-section of the universe, showing objects at different distances and stages in cosmic history. They range from cosmic near neighbors to objects seen in the early years of the universe. (See the Hubble web page for this story to view a larger image.)

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Cosmos for the Next Generation

Thursday April 17, 2014

Are you watching Cosmos: A Spacetime Odyssey?  In the U.S., it airs on Sundays on Fox TV and on Mondays on National Geographic Channel. You can also see episodes online at CosmosOnTV.com. For space enthusiasts, astronomers, and others simply interested in learning more about our universe, this program is the one to see. It's the next generation of a series begun by Dr. Carl Sagan in 1980, a series that set a whole generation of astronomers and science writers on their career paths.

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Saturn May Have a New Moon

Tuesday April 15, 2014

Cassini Spots a New Object in Saturn's Rings

If you're out stargazing over the next few months, at some point, you will notice the planet Saturn. On these April nights, it's rising late in the evening (right now around 10 p.m. or thereabouts), so you have to stay up to find it. But, it's well worth the look. The rings alone give this planet an otherworldly and fascinating appearance.

Those of us who gaze at Saturn from our backyards aren't the only ones watching this planet. The Cassini spacecraft, which has been studying the Saturn system since 2004, has been our eyes, ears, and planetary science exploring, sending back incredible images and data.  It has sent the Huygens probe to the surface of Saturn's largest moon, Titan, returning amazing information about this weird world. Cassini has also found an ocean of salty water beneath the icy surface of the moon Enceladus, mapped the rings, and shown us the beauty of Saturn's ever-changing cloud tops. Recently, it documented the formation of a small icy object within one of the planet's outermost rings. It could be a new moon, forming from the chunks of ice that orbit Saturn and form its rings.

A possible new moon in Saturn's A ring.

A possible new moon of Saturn, discovered as part of a disturbance in Saturn's outermost A ring. Courtesy NASA/JPL-Caltech/Space Science Institute.

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Watch the Moon Turn Red

Friday April 11, 2014

simulated view of lunar eclipse

How the April 14-15, 2014 lunar eclipse could look during totality. The Moon will be near the bright star Spica. Created by Carolyn Collins Petersen using Stellarium open source software. Click image for a larger version.)

Experience a Total Lunar Eclipse!

On April 15th, in the wee hours of the morning, you have a chance to see one of nature's most awe-inspiring events: a total lunar eclipse. People are referring to this one as a Blood Moon because at totality (the darkest part of the eclipse), the Moon will appear a deep red color. Observers across the Americas, and parts of the Pacific will able to witness it beginning late Monday night April 14 into the early morning of April 15th. (For a complete list of what locations on Earth will see this eclipse, check out NASA's Eclipse Web page.)

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A Black Hole Cannibal at the Milky Way’s Heart

Monday April 7, 2014

How Black Holes Grow

Gas cloud headed toward the black hole in Milky Way Galaxy's heart.

For the past few years, astronomers have been watching with great interest as a cloud of gas called G2 gets ever closer to the black hole at the center of the Milky Way Galaxy. The cloud (shown in the image at left) is headed directly into Sagittarius A* (Sgr A* for short) and will get caught up in the accretion disk of material surrounding and feeding into our black hole. The collision is already starting to occur, although the largest mass of the cloud has not yet arrived at the disk. But, the outer edges are starting to feel the pull of the black hole and that is providing a unique opportunity for astronomers to watch as a black hole swallows up material.

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Ten Great Sky Sights for April 2014

Friday April 4, 2014

I've been a stargazer since I was a child, and continue to go out and explore the sky when the conditions are right. Skygazing is an easy pastime, and a rewarding one. Want to check out the planets Mars, Jupiter and Saturn? See the Moon turn red? Experience a meteor shower? They're all available on April evenings after the sky gets dark. You don't need any special equipment, but if you do have binoculars or a small telescope, use them. Here's a list of ten great sky sights for April for you to search out. Go to About.com's star chart page to make a sky map for your location and let's do some stargazing!

  1. Jupiter. The famed astronomer Galileo Galilei had only a small telescope to study this giant planet, but the four moons he saw changed our view of the solar system. These small worlds, the Galilean satellites are easy to spot with a good pair of binoculars and look even better through a telescope. Jupiter is the brilliant shining dot in the constellation Gemini, the Twins.
  2. Mars. The Red Planet is easy to spot with the naked eye this month. Just look for a brilliant reddish dot in the constellation Virgo late in the evening, well above the eastern horizon. It's not too far from the bright star Spica.If you happen to have a good-sized telescope, you might be able to make out some surface markings on Mars.
  3. The Moon. Want a great observing target throughout the month? Check out the Moon. The dark areas on heavily cratered surface are called "maria", which is Latin for "seas". You will also see some bright areas marked by splashy-looking rays. These are craters and the rays are where the material gouged out by long-ago impacts spread out across the surface.
  4. A Total Lunar Eclipse. On the evening of April 14th into the morning of the 15th, watch as the Moon passes through Earth's shadow in a total lunar eclipse.  It will gradually get dark as it moves through the penumbra. Later, the Moon will pass into the umbra - the darkest part of Earth's shadow. It will look darker and probably turn a coppery red color. The eclipse will be visible throughout North and South America, and parts of the lower Pacific basin, including Australia. Read More...

Penumbral Lunar Eclipse ... Oct 18, 2013

Friday October 18, 2013

The Moon will be full this evening.  A full moon occurs approximately once every calendar month, when the Earth is positioned between the Sun and the Moon, so that observers located on the unlit side of the Earth are directly facing the fully-lighted face of the Moon.

At this time, the Moon is normally near it's brightest as seen from Earth; however, this evening at around 7:30 PM EDT, a portion of the Moon will darken noticeably as it enters and passes through the shadow of the Earth.  This is known as a lunar eclipse.  This event may already be in-progress at moonrise if you live in the US.

Lunar eclipses don't occur every month because the Sun-Earth-Moon alignment is rarely along a straight line.  When they do occur, eclipses vary in degree from "partial" (where the Moon is only partly in the Earth's shadow) to "full", where the Moon is entirely darkened by the Earth's shadow.  This evening's lunar eclipse is of the "partial" variety, and is more specifically known as a "Penumbral Lunar Eclipse" because only the Moon's southern edge passes through the outer edge of the Earth's shadow.

You can learn more about tonight's eclipse on the NASA web site.

This will be the last lunar eclipse of the year 2013.  Enjoy!!

 

by James Toothman

Moon-Venus Conjunction

Tuesday September 10, 2013

Moon and Venus in close conjunction on Sunday September 8th, 2013.

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Sunday September 8th, 2013 photo of the Moon and Venus appearing together in close proximity in the twilight sky over New Jersey.  This apparent alignment in the sky as observed from Earth is known as a conjunction. Image taken using Canon EOS Rebel T2i with Sigma 18x250mm zoom lens, 1/8th second exposure.

by James Toothman

3-D Licious

Friday July 12, 2013

Every Trekkie knows that slightly glitchy food replicators will be commonplace by the 24th century, providing personalized meal service on-demand to the crew of every star ship. Menu choices then will be limitless! But how do we get there?

Rewind 300 years or so. To kick things off, NASA is giving a Texas-based engineering firm 6 months and 125 million dollars to learn how to make ... pizza.

Well, actually not just pizza. Though pizza is expected to be an early prototype, research contractor SMRC (Systems and Materials Research Corporation - Austin, TX) proposes to design machines that can serve up a wide variety of nutritious, if not delicious, foods from just a handful of raw ingredients. They've imagined lofty goals of widespread commercialization, possibly even the promise of averting a food war or putting an end to world hunger. Achieving success will depend upon radically extending the development of existing "additive manufacturing" technologies into the realm of cuisine.

More widely known as "3-D printing", additive manufacturing is so named because it quite literally builds 3-D objects by repeatedly depositing thin layers of material, adding one upon another until the desired final shape is complete. These 3-D printing devices function a lot like your everyday 2-D ink jet printer, except that they make multiple passes over the same surface. To print a pizza, the device follows a digital blueprint. The blueprint becomes the recipe. Instead of dispensing cyan, magenta, yellow, and black dyes onto paper, SMRC will blend sugars, starch, oils & fats, proteins, and water to concoct something hopefully resembling dough and cheese.

Historically, space food might generously be described as minimalistic. During the early years of space travel, size and weight were the primary considerations. It simply wasn't feasible to carry "real" foods, and so the earliest astronauts made do with freeze-dried chunks of protein and toothpaste-like tubes of goo.

As the space program progressed and spacecraft grew larger, so too did the menus. But these larger spacecraft also accommodated more astronauts, and for longer durations, raising the need to efficiently store even more food (and waste) for longer periods.

Even recently, Shuttle astronauts needed to pre-plan their meals months in advance of each space flight, under the careful guidance of a trained nutritionalist. The list of available menu items was, by comparison, surprisingly extensive ... basically the same ordinary grocery store foods that we all enjoy. However, only a small quantity of fresh breads, fruits, and vegetables, could be carried on each journey; most provisions were still specially prepared and packaged to reduce bulk, increase shelf life, and make eating them manageable in the microgravity of space.

Today, with an eye toward very long duration space flights to Mars, shelf-life has become the key factor. According to NASA, food stores for a manned mission to Mars would need a minimum shelf-life of 3-5 years, but the current generation of "rehydratable" and "thermostabilized" space food degrades over time and does not meet these requirements. SMRC reportedly hopes that the raw ingredients for their printable system could remain edible and nutritious for upwards of 30 years.

Is 3-D printed space food the way to go? I for one can't imagine planning all my meals years in advance, so being able to offer our astronauts countless spontaneous combinations of synthesized dishes would certainly seem to me to offer an advantage over the current method of recycling the same pre-planned menus week after week. Will synthesized food taste good? Taste necessarily may be only a secondary consideration for NASA, but one they will surely do their best to address ... a hungry astronaut is not a happy astronaut. Perhaps one day soon NASA can again honor Gene Roddenberry, visionary creator of "Star Trek", by naming their first tasty 3-Dessert after him: "Rodden-Berry Pie".

3-D printing is very trendy, sometimes controversial, and just now in it's infancy. If NASA can make printable food viable for space travel then it might just be around the corner for the rest of us too, joining the ranks of talking supercomputers, handheld portable communicators, and ion propulsion as fantasy-turned-fact. And yes, $125 million for pizza may sound expensive, but remember it will come with as many toppings as the astronauts like AND fast, free delivery to anywhere within low-Earth orbit in 30 minutes or less.

by James Toothman

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