Posted on by Fraser Cain

What’s Up This Week – Jan 3 – Jan 9, 2005

Monday, January 3 – For those of you who were brave enough to fight the cold this morning to look for the annual Quandrantid meteor shower? Bravo! But if bad skies or arctic temperatures kept you from viewing, you still have another opportunity because this unusual meteor shower peaks over a period of two days.

The Quadrantid meteor shower has been known to be an incredibly concentrated display – at times producing between 50 to 120 meteors in the northern hemisphere. It is infrequently observed simply because of low temperatures in the north and bad positioning in the south. Another reason we do not known much about this shower is the short period of time that it is active. The peak can only last a few hours! The meteoroid stream itself is vast, but very accurate predictions are difficult thanks to complex streams perturbed by Jupiter’s gravity. The precise source of the Quadrantid meteor wasn’t even discovered until December 2003! Just slightly over a year ago, Peter Jenniskens of NASA Ames Research Center found evidence that tied the Quadrantids to an extinct comet now known as asteroid 2003 EH1. Historical observations reveal this comet was visible some 500 years ago, but may have suffered some type of impact that caused it to break up. Because we hit this “debris stream” at a perpendicular angle, we are “in and out” rather quickly – making precise calculations difficult at best.

The Quadrantids are named for a constellation that no longer exists on modern star atlases – Quadrans Muralis. In 1922, the International Astronomical Society removed it (along with several others) from the overburdened sky maps leaving only 88 officially designated constellations. So where do you look? The accepted radiant for the Quadrantids has now been assigned to Bootes, but the stream kept its original name to help distinguish it from another annual January shower – the Bootids. Even though the constellation might be gone, your chances are still good of catching one of these “frosty meteors”! The hours after local midnight will be best as we move into January 4. Although the waning Moon will decrease the number you may see, be sure to watch for “colors” in the display. As meteors burn up in our atmosphere, they produce colors thanks to their chemical spectra and the Quadrantids are known to range from blue to green. Best of luck!

Tuesday, January 4 – Heads up for Africa and southwestern Australia! It’s your turn for an astronomical event as the Moon will occult Jupiter for your location in the early morning hours. (see? i haven’t forgotten you!) Timing is absolutely critical for this type of observation, so please visit this IOTA page for the precise path and list of times for your area. For those of us who will only see the Moon and Jupiter separated by less than 7 degrees, we wish you clear skies!

For sky watchers around 40 degrees north, this morning will mark the latest sunrise of the year. Why not take advantage this morning before beginning your busy day and have a look at the simple beauty of the ecliptic plane? To the east and down low on the horizon will be Mercury and Venus, above them (about 17 degrees to the west) will be tiny Mars. Almost overhead, and just slightly south will be Jupiter and west of it will be the Moon. Continue your visual journey to the far west as Saturn completes this lovely arc.

With plenty of time to spare before the Moon rises tonight, let’s try for a new Messier object. Located slightly more than 2 degrees northeast of Zeta Orionis and right on the celestial equator is a delightful area of bright nebula known as the M78 (NGC 2068). Often over-looked in favour of “the Great Orion Nebula”, this 8th magnitude diffuse area is easily captured with small scopes. Discovered by Mechain in 1789, the M78 is part of the vast complex of nebulae and star birth that comprise the Orion region. Fueled by twin magnitude 10 stars, the nebula almost appears to the eye to resemble a “double comet”. Upon close scrutiny, observers will note two lobes separated by a dark band of dust and each lobe bears its own designation – NGC 2067 to the north and NGC 2064 to the south. While studying, you will notice the entire area is surrounded by a region of absorption, making the borders appear almost starless! The M78 itself is filled with T Tauri type stars… But we’ll explore why these variables are incredible as we examine their prototype later this week.

Wednesday, January 5 – Tonight let’s take a journey just a breath above Zeta Tauri and spend some time with the most famous supernova remnant of all – the M1. Factually, we know the “Crab Nebula” to be the remains of an exploded star recorded by the Chinese in 1054. We know it to be a rapid expanding cloud of gas moving outward at a rate of 1,000 km per second, just as we understand there is a pulsar in the center. We also know it as first recorded by John Bevis in 1758, and then later cataloged as the beginning Messier object – penned by Charles himself some 27 years later to avoid confusion while searching for comets. We see it revealed beautifully in timed exposure photographs, its glory captured forever through the eye of the camera — but have you ever really taken the time to truly study the M1? Then you just may surprise yourself…

In a small telescope, the “Crab Nebula” might seem to be a disappointment – but do not just glance at it and move on. There is a very strange quality to the light which reaches your eye, even though at first it may just appear as a vague, misty patch. To small aperture and well-adjusted eyes, the M1 will appear to have “living” qualities – a sense of movement in something that should be motionless. This aroused my curiosity to study and by using a 12.5″ scope, the reasons become very clear to me as the full dimensions of the M1 “came to light”.

The “Crab” Nebula holds true to so many other spectroscopic studies I have enjoyed over the years. The concept of differing light waves crossing over one another and canceling each other out – with each trough and crest revealing differing details to the eye – is never more apparent than during study. To truly watch the M1 is to at one moment see a “cloud” of nebulosity, the next a broad ribbon or filament, and at another a dark patch. When skies are perfectly stable you may see an embedded star, and it is possible to see six such stars. It is sometimes difficult to “see” what others understand through experience, but it can be explained. It is more than just the pulsar at its center teasing the eye, it is the “living” quality of which I speak -TRUE astronomy in action. There is so much information being fed into the brain by the eye!

I believe we are all born with the ability to see spectral qualities, but they just go undeveloped. From ionization to polarization – our eye and brain are capable of seeing to the edge of infra-red and ultra-violet. How about magnetism? We can interpret magnetism visually – one only has to view the “Wilson Effect” in solar studies to understand. What of the spinning neutron star at its heart? We’ve known since 1969 the M1 produces a “visual” pulsar effect! We are now aware that about once every five minutes, changes occuring in the neutron star’s pulsation effect the amount of polarization, causing the light waves to sweep around like a giant “cosmic lighthouse” and flash across our eyes. For now, l’ll get down of my “physics” soapbox and just let it suffice to say that the M1 is much, much more than just another Messier. Capture it tonight!!

Thursday, January 6 – Since we’ve studied the “death” of a star, why not take the time tonight to discover the “birth” of one? Our journey will start by identifying Aldeberan (Alpha Tauri) and moving northwest to bright Epsilon. Hop 1.8 degrees west and slightly to the north for an incredibly unusual variable star – T Tauri.

Discovered by J.R. Hind in October 1852, T Tauri and its accompanying nebula, NGC 1555 set the stage for discovery with a pre-main sequence variable star. Hind reported the nebula, but also noted that no catalog listed such an object in that position. His observance also included a 10th magnitude uncharted star and he surmised that the star in question was a variable. On either account, Hind was right and both were followed by astronomers for several years until they began to fade in 1861. By 1868, neither could be seen and it wasn’t until 1890 that the pair was re-discovered by E.E. Barnard and S.W. Burnham. Five years later? They vanished again.

T Tauri is the prototype of this particular class of variable stars and is itself totally unpredictable. In a period as short as a few weeks, it might move from magnitude 9 to 13 and other times remain constant for months on end. It is about average to our own Sun in temperature and mass – and its spectral signature is very similar to Sol’s chromosphere – but the resemblance ends there. T Tauri is a star in the initial stages of birth!

So what exactly are T Tauri stars? They may be very similar in ways to our own Sun but they are far more luminous and rotate much faster. For the most part, they are located near molecular clouds and produce massive outflows of this material in accretion as evidenced by the variable nebula, NGC 1555. Like Sol, they produce X-ray emissions, but a thousand times more strong! We know they are young because of the spectra – high in lithium – which is not present at low core temperatures. T Tauri has not reached the point yet where proton to proton fusion is possible! Perhaps in a few million years T Tauri will ignite in nuclear fusion and the accretion disk become a solar system. And just think! We’re lucky enough to see them both…

Friday, January 7 – For mid-northern latitudes, this morning will be the last chance to see the crescent Moon (gosh, aren’t you crushed?) before it goes new. But for those living in northwestern America, the treat will be extra special as the Moon will occult Antares! Be sure to visit IOTA for precise times and locations.

Are your ready for a real weekend treat? Then look no further than the night sky above as Comet Machholz will be putting on one of the best shows of the year as it appears around 2 degrees west of the Plieades star cluster!

Near the ecliptic, and with a rough visual magnitude of slightly less than 2, the Plieades (M45) will appear brighter than Comet Machholz – but current information suggests that C/2004 Q2 will have achieved 4th magnitude by that time – making both easy unaided-eye objects. Average binoculars span a field of around 4 degrees, so both objects should fill the field of view! While watching, take the time to practice with size, distance and magnitude observations. The M45 spans approximately 1.2 degrees of sky – how does the size of the comet’s coma compare? Since the two are around 2 degrees apart, how long does the tail seem to span? The brightest of the major stars in the Plieades is 2.8 and the dimmest approximately 5.6 – by defocusing, how bright does Comet Machholz nucleus appear in comparison? You know what direction the M45 is from Machholz, which way does the twin tail appear to go?

Of course, you needn’t truly worry about any of this just to enjoy the view! I’ll race you there…

Saturday, January 8 – So are you ready for a real challenge? Then take advantage of dark sky time to head toward Orion. Tonight our aim is toward a single star – but there is much more hiding there than just a point of light!

Our goal is the eastern-most star in the “belt”, Zeta Orionis, or better known as Alnitak. At a distance of some 1600 light years away, this 1.7 magnitude beauty contains many surprises – the first being that Zeta is a triple system. Fine optics, high power and steady skies will be needed to reveal this challenge! Want more? Then look about 15′ east and you will see that Alnitak resides in a fantastic field of nebulosity which is illuminated by our tripartite star. The NGC2024 is an outstanding area of emission that holds a rough magnitude of 8 – viewable in small scopes but will require dark sky. So what’s so exciting about a fuzzy patch? Then look again, for this beauty is known as the “Flame”! Larger telescopes will deeply appreciate this nebula’s many dark lanes, bright filaments and unique shape! Still not enough? Then break out the big scopes and put Zeta out of the field of view to the north at high power and allow your eyes to re-adjust. When you look again, you will see a long, faded ribbon of nebulosity called IC434 to the south of Zeta that stretches for over a degree. The eastern edge of the “ribbon” is very bright and mists away to the west… But hold your breath and look almost directly in the center. See that dark notch with two faint stars south of it? You have now located one of the most famous of the Barnard dark nebula – B33.

You may exhale now. The B33 is also known as the “Horsehead Nebula”. The “Horsehead” is a very tough visual object – the classic chess piece shape only seen in photographs – but those of you who have large aperture can see a dark “node” that is improved with a filter. The B33 itself is nothing more than a small area comsically (about 1 light year in expanse) of obscuring dark dust, non-luminous gases, and dark matter – but what an incredible shape! If you do not succeed at first attempt? Do not give up. The “Horsehead” is one of the most challenging objects in the sky and has been observed with apertures as small as 150mm. Keep trying! This just might be your lucky “Knight”…

Sunday, January 9 – Tonight’s destination will be within our own solar system, but with good reason! As we know, all the orbits of the planets are tilted relative to our own Earth’s orbit. This means that each time a planet completes an orbit around the Sun, it must pass over our own orbital plane twice. One time it will move from above Earth’s orbit to below, and the next it will go in the opposite direction. Tonight, Saturn will cross Earth’s orbital plane from below to above and this action of passing is what is astronomically known as the “ascending node”. It is rather special because it will be another 29 years before Saturn completely orbits the Sun and achieves the “ascending node” again!

So what does that mean to those wishing to view Saturn tonight? Not much other than it is a “cool” astronomy fact. The best time to view Saturn is at opposition which won’t occur for about another year. The most interesting part about watching Saturn right now is the ring system. Like our Earth, Saturn tilts on its axis. Since the ring system is equatorial, our best views of the rings themselves come when Saturn is highly inclined. As luck would have it, Saturn is well placed right now for just such viewing. Right now, it’s saturnian winter for the Ring King’s northern hemisphere, so get thee out there an explore! Small telescopes at high power can make out the pencil slim line of the Cassini Division on a stable night, while larger telescopes can easily spot other ring divisions. Be sure to watch for Saturn’s many moons as well. Titan is easily visible to the smallest of scopes and even a 114mm can reveal as many as four others. Enjoy it tonight!

Is it gone yet? Yes! New Moon week is about to begin, so expect some more challenging objects for veteran observers next time. For those just beginning? Don’t worry. There will be plenty for you to explore as well! I would like to thank all of you who take time to write – you’ll never know how much I appreciate it! (and earthlink users? please check your rejected mail for answers to your questions.) Until next time, ask for the Moon but keep reaching for the stars!

Light speed… ~Tammy Plotner

Posted on by Fraser Cain

Cassini’s Route Past Iapetus

NASA’s Cassini spacecraft is set to cap off 2004 with an encounter of Saturn’s ying-yang moon Iapetus (eye-APP-eh-tuss) on New Year’s Eve.

This is Cassini’s closest pass yet by one of Saturn?s smaller icy satellites since its arrival around the ringed giant on June 30 of this year. The next close flyby of Iapetus is not until 2007.

Iapetus is a world of sharp contrasts. The leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow.

Cassini will fly by the two-toned moon at a distance of approximately 123,400 kilometers (76,700 miles) on Friday, Dec. 31. This flyby brings to an end a year of major accomplishments and rings in what promises to be a year filled with new discoveries about Saturn and its moons.

“I can think of no better way than this to wrap up what has been a whirlwind year,” said Robert T. Mitchell, program manager for the Cassini mission at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “The new year offers new opportunities, and 2005 will be the year of the icy satellites.”

In 2005 Cassini will have 13 targeted encounters with five of Saturn’s moons. “We have 43 close flybys of Titan still ahead of us during the four-year tour. Next year, eight of our 13 close flybys will be of Titan. We will also have a number of more distant flybys of the icy satellites, and let’s not forget Saturn and the rings each time we come around,” said Mitchell.

With a diameter of about 1,400 kilometers (890 miles), Iapetus is Saturn’s third largest moon. It was discovered by Jean-Dominique Cassini in 1672. It was Cassini, for whom the Cassini-Huygens mission is named, who correctly deduced that one side of Iapetus was dark, while the other was white.

Scientists still do not agree on whether the dark material originated from an outside source or was created from Iapetus’ own interior. One scenario for the outside deposit of material would involve dark particles being ejected from Saturn?s little moon Phoebe and drifting inward to coat Iapetus. The major problem with this model is that the dark material on Iapetus is redder than Phoebe, although the material could have undergone chemical changes that made it redder after its expulsion from Phoebe. One observation lending credence to the theory of an internal origin is the concentration of material on crater floors, which implies that something is filling in the craters. In one model proposed by scientists, methane could erupt from the interior and then become darkened by ultraviolet radiation.

Iapetus is odd in other respects. It is the only large Saturn moon in a highly inclined orbit, one that takes it far above and below the plane in which the rings and most of the moons orbit. It is less dense than objects of similar brightness, which implies it has a higher fraction of ice or possibly methane or ammonia in its interior.

The last look at Iapetus was by NASA’s Voyager 1 and 2 spacecraft in 1980 and 1981. The Cassini images will be the highest resolution images yet of this mysterious moon. The Iapetus flyby by Cassini follows the successful release of the Huygens probe on December 24.

More information on the Cassini-Huygens mission is available at: http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter. The European Space Agency built and managed the development of the Huygens probe and is in charge of the probe operations. The Italian Space Agency provided the high-gain antenna, much of the radio system and elements of several of Cassini’s science instruments.

Cassini spacecraft targeted satellite encounters for 2005:

Titan: January 14, 2005
Titan: February 15, 2005
Enceladus: March 9, 2005
Titan: March 31, 2005
Titan: April 16, 2005
Enceladus: July 14, 2005
Titan: August 22, 2005
Titan: September 7, 2005
Hyperion: September 26, 2005
Dione: October 11, 2005
Titan: October 28, 2005
Rhea: November 26, 2005
Titan: December 26, 2005

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Your Interview with Dr. Jean-Pierre Lebreton

Just how dense is Titan’s atmosphere expected to be, and how did that influence the design of the probe? – Kepesk

The atmosphere of Titan is denser and thicker than that of the Earth. The surface pressure is 1.5 times that on Earth (1500 mbar). But because Titan gravity is 1/6 of Earth’s, the atmosphere is much more expanded. Huygens will brake at about 300 km altitude, while Earth re-entry vehicles brake at about 60 km altitude.

The probe was designed to brake as high as possible for allowing in-situ sampling of the atmosphere as high as possible (about 165 km). It required a large heat-shield.

The heat-shield design was influenced by the presence of methane in the atmosphere. Methane and nitrogen break apart in the shock layer that forms in front of the probe during the hypersonic entry and form the CN radical which is a strong emitter of violet radiation (during the entry, Huygens radiates as much as 1000 sun for about 30 sec). CN radiates a lot of heat on the heat-shield. The amount of radiation (heat flux) on Huygens heat shield is 3 to 4 times higher than if we would enter in a pure nitrogen atmosphere.

How did Titan “collect” so much organic material and get such a dense atmosphere? Did Titan “collect” the stuff or was the moon lucky and manage not to lose it? – baselle

This is a fundamental question. Answering it is a major scientific objective of the Cassini-Huygens mission. Most (if not all) of the organic matter in Titan’s atmosphere and on the surface comes from the chemical processing of methane. The origin of methane is one of the big mysteries that Huygens should help to solve.

What design considerations were made on the probe to help ensure it would survive a trip to Saturn that took it on flybys to a few other planets along the way? – dave_f

The main design considerations for Huygens long trip to Saturn were to ensure that the temperature of its batteries would be kept cool enough. Huygens is protected by a multi-layer insulation thermal blanket and protected from the sun by the orbiter high-gain antenna until we reached Jupiter. Regular (bi-annual) activations of Huygens during a few hours were designed to monitor its health and calibration and to activate movable instrument mechanisms for their maintenance.

Survived landing will be a bonus, not the goal, with this in mind, was there anything other than timing and synchronicity with the orbiter considered when choosing a “landing” site? – tiderider

Huygens is not a lander. So I prefer to talk about impact or touchdown site. The impact site was not specifically chosen. The main drivers were: i) the entry angle in the atmosphere, ii) the need to descend in the sunlit side of Titan, iii) a low to medium latitude descent, but away from the equator for best wind measurements, and iv) an optimized geometry for the radio link with the orbiter.

Supposing that remarkable observations where recorded by Huygens, how could such observations contribute to our understanding of the solar system evolution? – Keemah

The detailed in-situ measurements by Huygens will be combined with the several-year global observations by the Cassini orbiter during its planned 45+ (more if the mission is extended) Titan flybys in order to better understand the weather on Titan, the chemical composition of the atmosphere, the origin and fate of the methane. In-situ isotopic measurements are a key for understanding the origin and evolution of Titan’s atmosphere. Understanding why Titan has a thick atmosphere (the only moon in the solar system to have a substantial atmosphere) will allow testing theories of planetary formation and evolution.

Are there some atmospheric (or even surface) conditions expected to disturb data transmission from Huygens to Cassini? – Lamahe

The atmosphere is transparent to radio communication between Huygens and Cassini (at 2 GHz). Too large a swing under the parachute may disturb the communication for a few seconds but Huygens will transmit on two radio channels. Key data are transmitted on the two channels but delayed by 6 sec on one of the two channels. This delay will allow all important data to be recovered if the link is interrupted for a short time.

If all goes well, how soon will detailed information about what did the probe observe be made available to the public? Is there a period when certain scientists have exclusive access? – antoniseb

Information will be made available to the public within hours after the data are received on earth on 14th January. Scientists will make every effort to make as much information as possible to the public. But scientists will also publish their research results in scientific literature within months. All Huygens data will be made available to the wide scientific community and to the public at large through ESA and NASA Planetary data archives in 2006.

What advice would you give someone who’s willing to work in space research? – Ola D.

You need to get a good education is mathematics, physics and chemistry, but also in literature and history of sciences in order to be able to communicate your research results to the public. You also need to be motivated to embrace a research career as jobs are difficult to get and not always well paid. If you want to undertake planetary research you need patience and to be unselfish. It took more than twenty years to get to Saturn from mission idea to the arrival. It will take years and decades to analyze all the data that will be returned by Cassini-Huygens. A mission such as Cassini-Huygens goes across generations. Cassini-like missions to Uranus and Neptune will take longer. But it is so exciting to be involved in such voyages that I would encourage all school boys and girls to study sciences and take a chance. It’s worth it. One more piece of advice. Cassini-Huygens is a true example of highly successful international collaboration. Learn a few languages as it will help to enjoy your trips abroad and best appreciate the multi-cultural environment you will work in as I am convinced that planetary exploration must be undertaken through multi-national collaborations.

Posted on by Fraser Cain

Banda Aceh from Space

Posted on by Fraser Cain

What’s Up This Week – Dec 27 – Jan 2, 2005

Image credit: NOAO
Monday, December 27 – No one likes to get up early, but this morning will be worth walking outside for as Mercury and Venus make a very close pairing on the horizon just before dawn. If you’re clouded out? Don’t worry. Both planets will keep their positions for several days!

With the almost full Moon rising not to long after the Sun sets, tonight let’s take the time to study another “double delight” – Gamma Arietis. Also known as Mesarthim, Gamma was one of the very first double stars to be discovered, well… rather accidentally! In 1664, Robert Hook was following a comet and stumbled upon this matched magnitude pair. At approximately 160 light years away, each of these two “white” stars are about three to four times more massive than our own Sun and are seperated by about 400 AU. Locked in an ancient embrace, the pair takes about 3,000 years to orbit each other. Since the time of their discovery, this duo’s relative orientation has remained virtually unchanged, but with the advent of modern measurement show they may have moved fractionally closer within the last 150 years. Does this mean they are drawing together? No. Like so many things we see from such a great distance, it is a matter of perspective and it is believed that we may be looking at their orbital pattern “edge-on”.

In the telescope at high power, Mesarthim is indeed a very close double, one who’s stars are precisely oriented north/south of each other. This one is quite delightful, for such similar magnitudes make them appear like “eyes” in the dark! (And if you are very, very good – you will see a tiny 9th magnitude star to the east. Fine optics and perfect stability will show this star also has a 13th magnitude companion.)

Tuesday, December 28 – Since the Moon won’t begin to rise for a short time after the skies turn dark, this would be a great opportunity to locate an easy Messier object – M34. If you remember previous study stars, Almach and Algol, you’re halfway there. Draw an imaginary line between them and look with your binoculars or finder scope just a shade north of center.

In binoculars, the M34 will show around a dozen fainter stars clustered together and perhaps a dozen more scattered around the field. Small telescopes at low power will appreciate the M34 for its resolvability and the distinctive “orange” star in the center. Larger aperture scopes will need to stay at lowest power to appreciate the 18 light year span of this 100 million year old cluster, but take the time to power up and study. You will find many challenging doubles inside!

Wednesday, December 29 – Is it gone yet? Nope. The Moon will rise a little later this evening, but we’re going to run ahead of it tonight and begin some studies in Auriga! Looking roughly like a pentagon in shape, start by identifying the brightest of these stars – Capella. Due south of it is the second brightest star, El Nath. By aiming binoculars at El Nath, go north about 1/3 the distance between the two and enjoy all the stars!

You will note two very conspicuous clusters of stars in this area, and so did Le Gentil in 1749. Binoculars will reveal the pair in the same field, as will telescopes using lowest power. The dimmest of these is the M38, and will appear vaguely cruciform in shape. At roughly 4200 light years away, larger aperture will be needed to resolve the 100 or so fainter members. About 2 1/2 degrees to the southeast you will see the much brighter M36. More easily resolved in binoculars and small scopes, this “jewel box” galactic cluster is quite young and about 100 light years closer!

There are many other fine things in this area, so scan around! We’ll be back…

Thursday, December 30 – Is it gone yet? No! The Moon will be along shortly, but not before we’ve had an opportunity to head for another northern “gem”, the M76.

Located in western Perseus just slightly less than 1 degree north/northwest of Phi, the M76 is often referred to as “The Little Dumbbell”. Originally discovered by Messier’s assistant Mechain in September of 1780, Charles didn’t get around to cataloging it for another six weeks. What a shame it took him so long to view this fine planetary nebula! Its central star is one of the hottest known, but it is its resemblance to the M27 that makes it so fascinating. Looking very much like a miniaturization of the much larger M27, the M76 is rather faint at magnitude 11, but is quite achievable in scopes of 114mm in aperture or larger. It is small, but its irregular shape makes this planetary nebula a real “class act”!

For our Southern Hemisphere friends, get thee out there and view Eta Carinae! First recorded by Halley in 1677, this nebular variable star left even the great Sir John Herschel at a loss to describe its true beauty and complexities. This “slow nova” is filled with all the wonders the we “northerners” can only dream about…

Friday, December 31 – Is it gone yet? No. The Moon will be around later tonight, but the year 2004 is just about ended. Try celebrating in a unique and inspiring way! Go observing…

In the hours before midnight, you could take a cosmic journey that spans millions of light years. In the northern hemisphere, visit with the Andromeda Galaxy again – or the Small and Large Magellanic Clouds if you live in the south. Feast your eyes on vast and wondrous displays of stars like the “Double Cluster” in Perseus, or the “Jewel Box” – Kappas Crucis star cluster. Rejoice in the birth of new stars by voyaging to the M42 – “Orion Nebula”… And remember the old by returning to the M1 – “Crab Nebula”. Take delight in the movements of our own solar system by hunting down the “Magnificent Comet Macholz”, or peeking in on Saturn’s rings. Perhaps the ISS will make a pass over your area tonight, or only a single star shine through. It may be something as spectacular as watching a meteor go down in a blaze of glory, or as quiet and contemplative as watching the Moon rise.

As we begin a New Year, just take a moment to look up at the stars and think about all the millions of years that they have been in the making and all the time that it has taken for the light to reach us. Salute!

Saturday, January 1 – Is it gone yet? No. The Moon will be on the scene later, but tonight’s goal with be a rather simple one – a star of singular beauty. Located northwest of Mu in the constellation of Lepus, is R Leporis – better known as “Hind’s Crimson Star”.

Discovered in October of 1845 by J.R. Hind, R Leporis will require optical aid to view since it is a variable that moves between approximately magnitude 6 to as low as magnitude 11 in about 432 days. As a carbon star, this particular example is well worth viewing for its intense ruby color. As R Leporis undergoes its changes, it produces amazing amounts of carbon. To understand what makes it dim, think of an oil lamp. As the carbon “soot” collects on the glass, like the star’s outer atmosphere, the light decreases until it is sloughed off and the process is repeated. At a rough distance of approximately 1500 light years, “Hind’s Crimson Star” will become an observing favorite. Enjoy!

Sunday, January 2 – Is it gone yet? No. The Moon will be around much later tonight, but the window of opportunity to view a spectacular comet is once again wide open.

Tonight the “Magnificent Comet Machholz” will be in the same field of view as 6 Tau Tauri. Having long ago achieved unaided eye brightness, C/2004 Q2 Machholz continues to delight observers the world over. The coma is easily seen in binoculars, and the twin ion and dust tails may still be observable on this date. Looking like a huge, unresolvable globular cluster, trying judging its visual magnitude for yourself by using nearby Xi and Omicron as guideposts. Defocus and compare these magnitude 4 stars to the comet’s brightness. Is the comet dimmer? Or about the same? There is no way of predicting exactly how bright comet Machholz will be in advance, but tonight you can make the call!

For very late night, or observers beginning early on the morning of January 3, keep a watch out for the annual Quadrantid meteor shower. Seeming to emanate from the constellation of Bootes, this annual shower can produce up to 60 meteors per minute, but has an unusual and unpredictable peak time. More information on the Quadrantids will be available in next week’s issue.

Until next week fellow SkyWatchers, I wish you all a peaceful and prosperous New Year. Keep looking up… I am! Light speed, ~Tammy Plotner

Posted on by Fraser Cain

Crew Begins Unloading Progress

An unpiloted Russian cargo ship linked up the International Space Station this evening, completing a two-day Christmas journey to deliver 2.5 tons of food, fuel, oxygen, water, supplies and holiday gifts to the crew.

The ISS Progress 16 craft automatically docked to the aft port of the Zvezda Service Module at 5:58 p.m. CST (2358 GMT) as the spaceship and the Station flew 225 statute miles over Central Asia. Within minutes, hooks and latches between the two ships engaged, forming a tight seal between the two vehicles. The docking occurred about 30 minutes later than planned so that the linkup could occur over Russian ground stations with the benefit of television from the cargo ship and real-time data.

As the Progress moved in for its linkup, Expedition 10 Flight Engineer Salizhan Sharipov was at the controls of a manual docking system in Zvezda, ready to take over the Progress? final approach in the unlikely event its automated docking system encountered a problem. But the docking was flawless. Station Commander and NASA Science Officer Leroy Chiao was nearby, taking video and still photos of the Progress arrival.

Launched from the Baikonur Cosmodrome in Kazakhstan on Thursday, the Progress is loaded with 1,234 pounds of propellant, 110 pounds of oxygen and air to help maintain the Station?s atmosphere, 926 pounds of water and more than 2,700 pounds of spare parts, life support system components and experiment hardware. The manifest also includes 69 containers of food, about a 112-day supply.

After an extended sleep period this evening, the crew will be awakened Sunday morning to conduct leak checks at the hatch interface between the Progress and Zvezda. They will open the Progress hatch shortly after noon CST (1800 GMT) Sunday to begin unloading its cargo.

Among the new items that arrived at the Station are laptop computers, new spares for U.S. spacesuits and components for the arrival next year of the European Automated Transfer Vehicle cargo craft.

Information on the crew’s activities aboard the Space Station, future launch dates, as well as Station sighting opportunities from anywhere on the Earth, is available on the Internet at:

http://spaceflight.nasa.gov/

Original Source: NASA News Release

Posted on by Fraser Cain

Asteroid Threat Ruled Out

Over the past week, several independent efforts were made to search for pre-discovery observations of 2004 mn4. These efforts proved successful today when Jeff Larsen and Anne Descour of the Spacewatch Observatory near Tucson, Arizona, were able to detect and measure very faint images of asteroid 2004mn4 on archival images dating to 15 March 2004. These observations extended the observed time interval for this asteroid by three months allowing an improvement in its orbit so that an Earth impact on 13 April 2029 can now be ruled out.

As is often the case, the possibility of future Earth impacts for some near-Earth objects cannot be entirely ruled out until the uncertainties associated with their trajectories are reduced as a result of either future position observations, or in this case, heretofore unrecognized, pre-discovery observations. When these additional observations were used to update the orbit of 2004 MN4, the uncertainties associated with this object’s future positions in space were reduced to such an extent that none of the object’s possible trajectories can impact the Earth (or Moon) in 2029.

In the accompanying diagram, the most likely position of asteroid 2004 MN4 is shown at the end of the blue line near the Earth on 13 April 2029. However, since the asteroid’s position in space is not perfectly known at that time, the white dots at right angles to the blue line are possible alternate positions of the asteroid. Neither the nominal position of the asteroid, nor any of its possible alternative positions, touches the Earth, indicating that an Earth impact in 2029 is ruled out.

The passage of the asteroid by the Earth in 2029 alters its subsequent trajectory and expands the asteroid’s position uncertainty region (i.e., the line of white dots increases in extent) so the asteroid’s subsequent motion is less certain than it was prior to the 2029 close Earth approach. However, our current risk analysis for 2004 MN4 indicates that no subsequent Earth encounters in the 21st century are of any concern.

Original Source: NASA News Release

Posted on by Fraser Cain

Opportunity Finds its Heat Shield

After six fruitful months exploring the interior of “Endurance Crater,” the Opportunity rover has successfully climbed out of the crater onto the surrounding flatland of Meridiani Planum. Once out, the rover examined some of its own tracks that it had laid down prior to entering the crater. It compared them side-by-side with fresh tracks in order to observe any weathering effects in the intervening 200 sols. Opportunity is now making its way toward an engineering examination of its heat shield, which is located about 200 meters (220 yards) from the edge of Endurance. Now that the vehicle is on the relatively flat plain rather than tilted toward the Sun on the north-facing inner slope of the crater, electrical output from its solar array has declined by about 15 percent. Opportunity remains in excellent health as it begins a new phase of exploration.

Sol 312 and 313 were planned in a single planning cycle. Opportunity was still inside Endurance Crater. On sol 312 the plan began with backing up and using the panoramic camera and miniature thermal emission spectrometer to observe a rock target called “Wharenhui,” which had been treated with the rock abrasion tool on earlier sols. Subsequent commands were to turn cross-slope, drive 7 meters (23 feet), turn upslope, and drive an additional 6 meters (20 feet) uphill. Opportunity performed the drive perfectly, ending up approximately 5 meters (16.4 feet) from the rim of Endurance Crater. Opportunity’s tilt went from 25 degrees pre-drive to 19 degrees post-drive.

Sol 313 was a restricted sol because results from the sol 312 drive were not available for planning sol 313. That meant that no driving or robotic-arm activities were permitted. So Opportunity performed about two hours of observations using the panoramic camera and miniature thermal emission spectrometer and then went to sleep in the early afternoon. The rover woke up to support late-afternoon and early-morning communication relays by the orbiting Mars Odyssey.

Sols 314 through 316 were planned in another single planning cycle. The plan was to complete the egress from Endurance Crater on sol 315, so sol 314 was another remote sensing sol. This would be the last full sol inside Endurance. Opportunity spent about two and a half hours observing with the panoramic camera and miniature thermal emission spectrometer. It also performed a nighttime observation with the miniature thermal emission spectrometer just before midnight. To ensure that Opportunity had adequate power, the early-morning communication-relay session with Odyssey was canceled and Opportunity went into a modified deep sleep after completing the late-night observation.

Sol 315 was the big day for Opportunity. The rover was finally going to leave Endurance Crater after spending 181 sols there! Opportunity was instructed to drive 7 meters (23 feet) up and out of the crater. It was a textbook drive. Everything went as planned and Opportunity had finally, successfully completed a long and detailed series of observations inside Endurance. Opportunity ended up on the plains of Meridiani ready to begin the next chapter of its adventures.

Sol 316 was the third sol of a three-sol plan, and because Opportunity had driven on sol 315, sol 316 was restricted to remote-sensing observations. The rover performed about two hours of remote sensing and went to sleep. Out on the plains, Opportunity went from a northerly tilt that is very good for solar exposure, to a southerly tilt that is not so good for solar exposure. The tilt was expected to be as high as 10 degrees, but Opportunity’s actual tilt was about 5 degrees. Daily output from the solar panels went from 840 watt-hours in the crater, to 730 watt-hours on the plains.

Since the team continues to be operating in restricted sol mode, sols 317 and 318 were planned together as a two-sol plan. For sol 317, the science team elected to drive toward wheel tracks that Opportunity had made before entering Endurance Crater. The rover backed up about 5 meters (16.4 feet), performed some mid-drive imaging, and then continued another 10 meters (33 feet) to put the old rover tracks into the work volume of the robotic arm. Sol 318 was another remote-sensing sol, during which Opportunity imaged its still-distant heat shield and conducted a miniature thermal emission spectrometer observation of the tracks.

After the drive, both old and new tracks were directly in front of the rover. On sol 319 Opportunity captured microscopic imager mosaics of both types of tracks, then drove about 40 meters (131 feet) closer to the heat shield, which will be examined carefully in future sols. Sol 319 ended on Dec. 17.

Original Source: NASA News Release

Posted on by Fraser Cain

Huygens is On Its Way

The European Space Agency?s Huygens probe was successfully released by NASA?s Cassini orbiter early this morning and is now on a controlled collision course toward Saturn?s largest and most mysterious moon, Titan, where on 14 January it will make a descent through one of the most intriguing atmospheres in the solar system to an unknown surface.

The separation occurred at 02:00 UTC (03:00 CET): A few minutes after separation, Cassini turned back to Earth and relayed back information about the separation. This signal then took 1 hour and 8 minutes to cross the 1.2 billion kilometres separating the Cassini spacecraft and Earth.

?Today?s release is another successful milestone in the Cassini/Huygens odyssey?, said Dr David Southwood, ESA?s Director of Science Programmes. ?This was an amicable separation after seven years of living together. Our thanks to our partners at NASA for the lift. Each spacecraft will now continue on its own but we expect they?ll keep in touch to complete this amazing mission. Now all our hopes and expectations are focused on getting the first in-situ data from a new world we?ve been dreaming of exploring for decades?.

Final stage of a seven-year odyssey
The Cassini/Huygens mission, jointly developed by NASA, ESA and the Italian space agency (ASI), began on 15 October 1997, when the composite spacecraft were launched from Cape Canaveral, Florida, atop a Titan 4B/Centaur vehicle. Together, the two probes weighed 5548 kg at launch and became the largest space mission ever sent to the outer planets. To gain sufficient velocity to reach Saturn, they had to conduct four gravity-assist manoeuvres by flying twice by Venus, once by the Earth and once by Jupiter. On 1 July Cassini/Huygens eventually became the first spacecraft to enter an orbit around Saturn.

On 17 December, while on its third orbit around the ringed planet, the Cassini orbiter performed a manoeuvre to enter a controlled collision trajectory towards Titan. As planned, a fine tuning of the trajectory took place on 22 December to place Huygens on its nominal entry trajectrory. While Huygens will remain on this trajectory till it plunges into Titan?s atmosphere on 14 January, the orbiter will perform a deflection manoeuvre on 28 December to avoid crashing onto the moon. Today?s separation was achieved by the firing of pyrotechnic devices. Under the action of push-off springs, ramps and rollers, the probe was released at a relative velocity of about 0.3 m/s with a spin rate of 7 rpm. Telemetry data confirming the separation were collected by NASA?s Deep Space Network stations in Madrid, Spain and Goldstone, California, when the telemetry playback signal from Cassini eventually reached the Earth.

The Huygens probe is now dormant and will remain so for its 20-day coast phase to Titan. Four days before its release, a triply-redundant timer was programmed in order to wake-up the probe?s systems shortly before arrival on Titan.

Exploring Titan?s atmosphere
Huygens is scheduled to enter Titan?s atmosphere at about 09:06 UTC (10:06 CET) on 14 January, entering at a relatively steep angle of 65? and a velocity of about 6 km/s. The target is over the southern hemisphere, on the day side. Protected by an ablative thermal shield, the probe will decelerate to 400 m/s within 3 minutes before it deploys a 2.6 m pilot chute at about 160 km. After 2.5 seconds this chute will pull away the probe?s aft cover and the main parachute, 8.3 m in diameter, will deploy to stabilise the probe. The front shield will then be released and the probe, whose main objective is to study Titan?s atmosphere, will open inlet ports and deploy booms to collect the scientific data. All instruments will have direct access to the atmosphere to conduct detailed in-situ measurements of its structure, dynamics and chemistry. Imagery of the surface along the track will also be acquired. These data will be transmitted directly to the Cassini orbiter, which, at the same time, will be flying over Titan at 60 000 km at closest approach. Earth-based radiotelescopes will also try to detect the signal?s tone directly.

Huygens changing its parachutes
After 15 minutes, at about 120 km, Huygens will release its main parachute and a smaller 3 m drogue chute will take over to allow a deeper plunge through the atmosphere within the lifetime of the probe?s batteries.

The descent will last about 140 minutes before Huygens impacts the surface at about 6 m/s. If the probe survives all this, its extended mission will start, consisting in direct characterisation of Titan?s surface for as long as the batteries can power the instruments and the Cassini orbiter is visible over the horizon at the landing site, i.e. not more than 130 minutes.

At that time, the Cassini orbiter will reorient its main antenna dish toward Earth in order to play back the data collected by Huygens, which will be received by NASA?s 70-m diameter antenna in Canberra, Australia, 67 minutes later. Three playbacks are planned, to ensure that all recorded data are safely transmitted to Earth. Then Cassini will continue its mission exploring Saturn and its moons, which includes multiple additional flybys of Titan in the coming months and years.

A probe deep into space and time
Bigger than Mercury and slightly smaller than Mars, Titan is unique in having a thick hazy nitrogen-rich atmosphere containing carbon-based compounds that could yield important clues about how Earth came to be habitable. The chemical makeup of the atmosphere is thought to be very similar to Earth?s before life began, although colder (-180?C) and so lacking liquid water. The in-situ results from Huygens, combined with global observations from repeated flybys of Titan by the Cassini orbiter, are thus expected to help us understand not only one of the most exotic members of our Solar System but also the evolution of the early Earth’s atmosphere and the mechanisms that led to the dawn of life on our planet.

Europe?s main contribution to the Cassini mission, the Huygens probe, was built for ESA by an industrial team led by Alcatel Space. This 320 kg spacecraft is carrying six science instruments to study the atmosphere during its descent. Laboratories and research centres from all ESA member countries, the United States, Poland and Israel have been involved in developing this science payload. The Huygens atmospheric structure instrument package (HASI) will measure temperature and pressure profiles, and characterise winds and turbulences. It will also be able to detect lightning and even to measure the conductivity and permittivity of the surface if the probe survives the impact. The gas chromatograph mass spectrometer (GCMS) will provide fine chemical analysis of the atmosphere and the aerosols collected by the aerosol collector and pyrolyser (ACP). The descent imager/spectral radiometer (DISR) will collect images, spectra and other data on the atmosphere, the radiation budget, cloud structures, aerosols and the surface. The doppler wind experiment (DWE) will provide a zonal wind profile while the surface science package (SSP) will characterise the landing site if Huygens survives the impact.

The Cassini-Huygens mission is a cooperation between NASA, the European Space Agency and ASI, the Italian space agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, is managing the mission for NASA?s Office of Space Science, Washington. JPL designed, developed and assembled the Cassini orbiter.

Original Source: ESA News Release

Posted on by Fraser Cain

Asteroid Threat Upgraded to 1 in 45

The probability that Asteroid 2004 MN4 will strike the Earth on April 13, 2029 has actually been upgraded to a 1-in-43 chance now that more observations have been made. The asteroid has reached an uprecedented 4 on the Torino scale. Of course, this still means that there’s a 98% chance that it’ll completely miss the Earth. The space rock is 400 metres (1,300 feet) across, so a direct impact with our planet would cause a significant amount of damage on a regional level. Update: as of Dec. 28th, the probability has been significantly downgraded thanks to further observations. It’ll definitely miss.