Saturday, July 23, 2011

Now Playing At The Sky Cinema... The Moon, Mars and Aldebaran

By Tammy Plotner

Be on morning alert from July 26 through July 28 as the Moon, Mars and Aldebaran put on a delightful sky show that doesn't require any special equipment - just cooperative weather! While this motion picture doesn't have any sound, what it will have is color to delight the eye.

When it comes to viewing the night sky, most people don't perceive much color. Things mostly appear black and white - with a little gray on the Moon thrown in for good measure. With experience, most skywatchers easily pick out blue stars and faded green in nebula, but what really gets our hearts ticking is red. And very few stars show that ruddy hue to unaided vision as well as the eye of Taurus the Bull - Aldebaran.

On the morning of July 26th, about an hour before dawn, the waning crescent Moon will be very close to Alpha Tauri and the contrast will make for a spectacular showing. The following morning, it will hover just above Mars and slide into position just below on July 27th. Take the time to really look at what you're seeing. Of the three principle players, the only one that generates its own light is Aldebaran... the rest are products of reflection. While the star's russet tone comes from being a cool giant, Mars color comes from iron oxide. Not only is the Moon reflecting back sunlight, but you'll also see the DaVinci effect where the "dark side" is gently illuminated as well.

Don't be surprised if folks you know ask you what's going on. Close conjunctions such as this excites the eye! Why? When it comes to our eyes, almost every photoreceptor has one ganglion cell receiving data in the fovea. That means there’s almost no data loss and the absence of blood vessels in the area means almost no loss of light either. There is direct passage to our receptors – an amazing 50% of the visual cortex in the brain! Since the fovea doesn’t have rods, it isn’t sensitive to dim lights. That’s another reason why the conjunctions are more attractive than the surrounding starfields. Astronomers know a lot about the fovea for a good reason: it’s is why we learn to use averted vision.

But don't avert your vision when it comes to enjoying this morning show!

Original News Source: McDonald Observatory StarDate News.

Thursday, July 21, 2011

Caught In The Web... Space Spider!

By Tammy Plotner

IC 342's dust structures show up vividly in red, in this infrared view from Spitzer. Image credit: NASA/JPL-Caltech

Look, he's crawling up my wall... Black and hairy, very small... Now he's up above my head... Hanging by a little thread. Nope. It's not Boris the Spider, it's spiral galaxy IC 342 and it's hanging out in the constellation of Camelopardalis. Thanks to NASA's Spitzer Space Telescope, we're able to peer through the dust clouds and sneak a peek at this arachnid appearing beastie.

Residing at an approximate distance of 10 million light-years, this impressive grand design spiral is difficult for details because it's located directly behind the disk of the Milky Way from our point of view. Tiny particles of interstellar dust, which measure just a fraction of a micron across, mimic the blue wavelength of light. These vast areas composed of silicates, carbon, ice, and/or iron compounds dim the light in a process called extinction - but using infrared vision can even the score. Line-of-sight stars from our galaxy appear blue/white and the blue haze around the galaxy's nucleus is from IC 342's collective starlight. It's gangly arms glow a soft crimson and clumps of newly forming stars radiate red.

It's small wonder the core of IC 342 appears so spooky. According to research, it has undergone a recent burst of star formation activity and is close enough to have gravitationally influenced the evolution of the local group of galaxies and the Milky Way. Can you observe Boris yourself? Absolutely. You'll find this magnitude 9 critter located along the galactic equator at RA 03h 46m 48.5s - Dec +68 05' 46". But beware... Its low surface brightness means you'll need a rich field telescope and good, dark skies.

Creepy, crawly... Creepy, crawly... Creepy, creepy, crawly, crawly...

Original News Source: JPL / Spitzer News.

Monday, July 11, 2011

Happy Anniversary, Neptune!

Written By Tammy Plotner

Today, July 11, 2011 marks the first full barycentric orbit of the planet Neptune since its discovery on the night of September 23-24, 1846. But there's a lot more to learn about this anniversary than just the date. Step inside and let's find out...

Pinpointing Neptune is a wonderful story. For many years we've been taught that the discovery of Neptune was done by mathematical calculations. This came about in 1821 when Alexis Bouvard was publishing his findings for Uranus and noticed a gravitational perturbation. This led him to hypothesize an unknown body was crossing the path. Then enter miscommunications, politics and John Adams...

"It is more likely that Adams realised that his proposed orbits were moving ever closer to a "forbidden" zone of resonance says Brian Sheen of Roseland Observatory. "Uranus orbits in 84 years, Neptune in 165, nearly a 2:1 resonance, this brings about much greater perturbations than were being measured. In fact the mid 19th century is a quiet period and much bigger swings are evident now."

In 1843 John Couch Adams used the data Bouvard proposed to begin working on a proposed orbit, but it would be several years later before Urbain Le Verrier verified its existence through physical observation - at the same time as Johann Gottfried Galle. Says Sheen; "It is often said that Adams never published his results. In fact a published paper was printed by November 1846 and appeared in the 1851 Nautical Almanack published in 1847."

Unknown to both at the time - and in a great twist of irony - Galileo had actually observed Neptune on December 28, 1612, and again on January 27, 1613, but didn't realize it was a planet. Small wonder he thought it was a fixed star, because as luck would have it, Neptune turned retrograde at the same time as his first observation! But Galileo was a great observer and made drawings of his find. Given all that we know today, it's pretty astonishing his limited equipment was able to perceive the blue planet, let alone realize its minor movement against the ecliptic meant something. After all, the very concept of the ecliptic plane was new!

"It has been known for several decades that this unknown star was actually the planet Neptune," says University of Melbourne physicist, David Jamieson. "Computer simulations show the precision of his observations revealing that Neptune would have looked just like a faint star almost exactly where Galileo observed it."

But we digress...

Today, July 11 would be the anniversary of Neptune's first full barycentric orbit - a celebration that has taken us 164.79 years of waiting to celebrate. Tomorrow, July 12 is the anniversary of Neptune's heliocentric completion. However, don't expect Neptune to be in the exact same position as it was on either date. While over 150 years is but a wink in the cosmic eye, it is certainly more than enough time for our solar system to have shifted That having been over simply said, what will happen at 21:48 and 24.6 seconds UT on July 11 is that Neptune will return to its exact longitudinal position in respect to the invariable plane. Is it close to its discovery point? Well, in a sense, yes. It will be within 1.5 arc seconds of its 1846 location relative to the barycentre. In visual terms, that's just a whisker.

Is Neptune observable right now? You betcha'. But it's not going to be easy... You'll find it at RA 22h 11m 14s - Dec 11 47' 1" at its longitudinal anniversary time. Need a map? Here you go...

As you can see, it's going to be quite late at night before Neptune has well cleared the horizon - but what an opportunity! Because of its small size, I recommend using a telescope for stability and printing a map from a planetarium program for more detailed star fields. It's certainly not going to look like the Voyager image above, but you can expect to see a slightly blue colored disk that averages about magnitude 8 (well within reach of smaller scopes). If you have never seen Neptune before, compare it in your mind's eye to one of Jupiter's moons and you'll be able to pick it out of starry background much easier.

Good luck, clear skies and happy anniversary Neptune!

Voyager Image of Neptune Courtesy of NASA.

Wednesday, July 6, 2011

The Sights And Sounds of Saturn's Super Storm

Written by Tammy Plotner

It's five hundred times bigger than any anything like it observed by the Cassini Mission in the last two years. It's encompassing approximately 2 billion square miles (4 billion square kilometers) of Saturn's surface. It's releasing lightning bolts at a rate of ten per second and it's happening ten times more frequently than other storms monitored since 2004. It's so intense that's it's even visible in larger amateur telescopes. Just what is it? A Saturn Super Storm...