Astro Tidbits

MeteorWayne · Jul 30, 2007

I don't know if this will work as intended, but thought I'd start the thread and give it a try. During the feeding and care of my voracious reading addiction (Science, Nature, Science News, Scientific American, Discover, Sky and Telescope, Astronomy. Invention and Tecnology, NYT Science times, SDC, ad infinitum...) I run across all sorts of little factoids. Don't know what to do with them at the time, but don't want to lose them, and the brain is somehwt unreliable, what with all the new info being stuffed in the top daily, a lot leaks out the bottom. So this thread is intended to be sort of a notepad of factoids. We'll see how it works. I'll start with the next post. Meteor Wayne <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

MeteorWayne · Jul 30, 2007

In the summer, the earth's motion around the sun is in the direction of the sun's rotation around the galaxy, so they add together. In the winter, the earth's motion subtracts from our rotation around the galaxy. Source: Science 448 p241 Jul 19 2007 <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Jul 30, 2007

Hi MeteorWayne, Interesting tidbit. I will throw this into the ring too: The Jupiter moon Io has several of the Solar System's tallest named mountains (not the actual tallest, they are on Mars). The tallest named mountain on the volcanic moon is Boosaulle Mons, rising some 15,850 metres / 52,000 feet, above its base. NASA / JPL & NASA / JHU. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

weeman · Jul 30, 2007

Both are very interesting <img src="/images/icons/wink.gif" /> I have always been fascinated with the Sun, so here's some Sun facts: The Sun's rotation period at its equator is only 25 days. Which is a very fast velocity considering it has a diamater which is 109 times that of Earth's! The temperature at the center of the Sun is about 15, 000, 000 degrees C. A physicist once calculated that if a pinhead was made to be the same temperature as the material at the core of the Sun, it would set everything alight for 100 km around it. Light waves from the Sun's core start out as gamma ray photons, traveling at light speed. However, it takes so long for them to reach the Sun's surface, and they interact with so many sub-atomic particles on their journey outwards, that by the time they reach the surface they emerge as ordinary visible light photons. <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

CalliArcale · Jul 30, 2007

On that note, the Sun's rotation is variable -- 25 days at the equator, and 36 days at the poles! AstroCappella: The Sun Song Music and Lyrics by Karen Smale Our star, the Sun is a big ball of gas And it's 99 percent of our solar system's mass It's an average star in our Milky Way Warming the Earth every day What powers our Sun and makes it so bright? Come on and tell me, what makes all that light? Hans Bethe long ago reached the conclusion It changes Hydrogen to Helium by nuclear fusion When fusion takes place light is created And it makes its way out (although rather belated) Through the Photosphere that's the part that we see The light comes out and shines on you and me About a million Earths could fit in the Sun But if you were there you wouldn't have much fun It's six thousand degrees at the photosphere And much hotter inside the solar atmosphere There are a few places where it's not so hot Like at the center of a big sunspot But heat is relative it's still pretty warm Sitting on a sunspot would do you great harm Galileo discovered sunspots What are those things, those funny dots? They're cooler parts, scientists feel Caused by a stronger magnetic field Those spots move around the face of the Sun Proving to all... solar rotation! A strange kind of movement, to do a full roll 25 days in the middle, 36 at the poles What about flares? I've heard of them here They're like giant explosions in the Chromosphere The magnetic fields above those sunspots Reconnecting again after being in knots Above the Chromosphere the Corona is placed It's millions of degrees and reaches way into space It's very thin, but read my lips That's the <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

MeteorWayne · Jul 30, 2007

Nice <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

silylene old · Jul 30, 2007

The sunspot cycle's 11 year timings and their intensity have a statistically significant correlation to the orbital periods and location of Jupiter and Saturn. This was first noted in a paper in the Astronomy Journal in 1965, and has been debated for decades. These planets' relative locations move the solar barycenter around, up to a solar radius outside of the sun's surface. This somehow (mechanism unknown) has an influence on the solar magnetic fields, and hence sunspot cycles. a very nice new paper in Phys Letters A 2007 by Palus et al confirms the influence <blockquote>In reply to:<hr />7. Conclusion Using the concept of synchronization analysis, we have quantitatively demonstrated that the solar activity cycle and the solar inertial motion are not independent. These two oscillatory phenomena are phase-synchronized during three epochs together accounting for almost half of the studied three-century observational data. It is important that techniques of nonlinear data analysis have a potential to contribute to resolving long disputed problems such as the nature of the solar activity cycle. In an independent study, PaluÅ¡ and NovotnÃ¡ [44] have recently observed nonlinear behavior of the sunspot cycle, namely its amplitude-frequency correlation. In this study we present quantitative evidence for a weak interaction of solar activity and gravity, i.e., for a weak influence of the movement of the giant planets of the solar system on the solar activity cycle. The existence of this weak interaction with still unknown physical mechanism does not mean that the SIM is</blockquote> <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center">- - - - - - - - - - - - - - - - - - - - - - </div><div class="Discussion_UserSignature" align="center">I really, really, really miss the "first unread post" function. </div> </div>

weeman · Jul 31, 2007

Hell yes I think thats fast! <img src="/images/icons/wink.gif" /> How large is Altair in comparison to our sun? <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

qso1 · Jul 31, 2007

http://solstation.com/stars/altair.htm According to the link above...1.8 times the Suns equatorial diameter. Now I gotta find some factoid...I like this thread. <div class="Discussion_UserSignature"> My borrowed quote for the time being:There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened. </div>

derekmcd · Jul 31, 2007

Ya think that's fast? Check this pulsar out. A 20 mile diameter at 716 revs per second would put its surface speed at about 25% the speed of light. (unless I did my math wrong). Now, that's fast. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

Smersh · Jul 31, 2007

According to this guy, the Earth is moving away from the Sun at a rate of approximately 1.5 cm per year ... http://curious.astro.cornell.edu/question.php?number=317 <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea." Churchill: "Nancy, if you were my wife, I'd drink it."Website / forums </div>

3488 · Jul 31, 2007

The Saturn moon Hyperion is the least dense known solid object in the solar system. Its average density is only 0.55 gcm3. Clearly this object is icy & has huge internal 'voids' or 'caverns'. NASA / JPL. Below Hyperion in Natural Colour from Cassini. NASA / JPL. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Jul 31, 2007

Tau Ceti. The star Tau Ceti lies 11.9 light years away form the Solar System. The diameter of Tau Ceti is 86 % of the sun (approx) & rotates on its axis once every 34 days at the equator (so a bit longer than the Sun). Mind you, like Vega (Alpha Lyrae), we are looking at Tau Ceti, almost pole on, so in the skies of Tau Ceti, our Sun would be a magnitude 2.6 Pole Star, in Southern Bootes, close to Tau Bootis (the sun would be at Right Ascension =13h 44m 04s, Declination =15Â° 56â€² 14â€³. Like the sun though, Tau Ceti appears to have a star spot cycle of approx 11 years. Tau Ceti has a mass of 81% of the Sun or about 267,300 Earth masses. Tau Ceti appears to be an old star, in the region of 9.4 GYO, as against 4.6 GYO for the Sun. Tau Ceti was one of two stars that were the subject of Project Ozma, in 1960. The first real attempt at SETI. Epsilon Eridani was the other subject. Tau Ceti has half the Sun's asbundance of Heavy Metals, in relation to its mass than the Sun. Also Tau Ceti appears to be at the centre of a huge asteroid / comet belt starting at 10 AU from Tau Ceti & extending to 55 AU from the star. Below, diagram showing our Sun (left) & Tau Ceti (right). Courtesy of R J Hall. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

robnissen · Jul 31, 2007

My favorite factoid: Well-known: The universe we can see, exploded (for lack of a better word) from an area less than the size of a quark about 13.7 gigs ago. Not Well-Known: No one knows what the size of the object was that exploded, it could have been the size of less than a quark, such that the universe we see is all there is, it could have been the size of earth, such that the universe we see is merely a trillon-trillionth of the entire universe, it could have been the size of the Milky Way (resulting in the universe we see to the full universe, as the same ratio as a quark to the Milky Way), it could have been the size of the visible universe, or it could have been infinite, which would result in an infinite universe expanding into an infinitely larger universe (whatever that means). Thinking about this always gives me a headache.

Saiph · Jul 31, 2007

Smersh: Actually that's approximately the rate at which the moon is receding from earth on a yearly basis. The earth recedes from the sun, according you your link, at approximately "a ten thousandth of a centimeter" a year. My factoid: The moon is actually one of the darkest objects in the solar system in terms of the % of light reflected, with an albedo (reflectivity) of: 0.12, similar to that of coal dust. p.s. mercury rivals this figure as well. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

3488 · Aug 1, 2007

The Uranus ice moon Miranda has the tallest known cliffs in the solar system. Verona Rupes reach at least 20 kilometres / 12 miles high. Verona Rupes appear to be a fault due to either a thrust fault on the upward side or a massive down thrown block on the lower side. The average surface temperatures on Miranda are minus 215 Celsius / 58 Kelvin. Water ice is as hard as rock at these cryogenic temperatures. Below Verona Rupes on Miranda. Imaged by Voyager 2. USGS / NASA / JPL. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

deapfreeze · Aug 1, 2007

This is going to turn into an astro encyclopedia MeteorWayne. I will have to keep an eye on this thread very interesting. <div class="Discussion_UserSignature"> William ( deapfreeze ) Hooperhttp://deapfreeze-amateur-astronomy.tk/ </div>

MeteorWayne · Aug 1, 2007

Ready for the Perseids? <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

3488 · Aug 1, 2007

Vega / Alpha Lyrae. Strong darkening observed around the equator of Vega suggests that the fifth brightest star in Earthâ€™s sky has a huge temperature difference of 4,000 degrees Fahrenheit from its cool equatorial region to its hot poles. Models of the star based on these observations suggest that Vega is rotating at 92 percent of the angular velocity that would cause it to physically break apart, an international team of astronomers announced. This result confirms the idea that very rapidly rotating stars are cooler at their equators and hotter at their poles, and it indicates that the dusty debris disk known to exist around Vega is significantly less illuminated by the starâ€˜s light than previously recognized. â€œThese findings are significant because they resolve some confusing measurements of the star, and they should help us gain a much better understanding of Vegaâ€™s circumstellar debris disk,â€ says Jason P. Aufdenberg, the Michelson Postdoctoral Fellow at the National Optical Astronomy Observatory in Tucson, Arizona. This debris disk arises mainly from the collision of rocky asteroid-like bodies. â€œThe spectrum of Vega as viewed from its equatorial plane, the same plane as the debris disk, should be about half as luminous as the spectrum viewed from the pole, based on these new results,â€ Aufdenberg explains. The team obtained high-precision interferometric measurements of the bright standard star Vega using the Center for High Angular Resolution Astronomy (CHARA) Array, a collection of six 1-meter telescopes located on Mount Wilson, California, and operated by Georgia State University. With a maximum baseline of 330 meters (1,083 feet), the CHARA Array is capable of resolving details as small as 200 micro-arcseconds, equivalent to the angular size of a nickel seen from a distance of 10,000 miles. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

3488 · Aug 1, 2007

Arcturus / Alpha Bootis. Arcturus is a type K1.5 IIIpe red giant star â€” the letters "pe" stand for "peculiar emission," which indicates that the spectrum of light given off by the star is unusual and full of emission lines. This is not too uncommon in red giants, but Arcturus has a particularly strong case of the phenomenon. It is at least 110 times more luminous than the Sun, but this underestimates its strength as much of the "light" it gives off is in the infrared; total power output is about 180 times that of the Sun. The lower output in visible light is due to a lower efficacy as the star has a lower surface temperature than the Sun. Arcturus is notable for its high proper motion, larger than any first magnitude star in the stellar neighborhood other than Î± Centauri. It is now almost at its closest point to the Sun, and is moving rapidly (122 km/s) relative to the solar system. Arcturus is thought to be an old disk star, and appears to be moving with a group of 52 other such stars. Its mass is hard to exactly determine, but may be about the same as the Sun, and is no more than 1.5 solar masses. Arcturus is likely to be considerably older than the Sun, and much like what the Sun will be in its red giant phase. Like other old red giats, Arcturus is a very slow rotater, taking two years to rotate once on its axis. This is almost identical of that of Aldebaran / Alpha Tauri. As one of the brightest stars in the sky, Arcturus has been the subject of a number of studies in the emerging field of astroseismology. Belmonte et al. (1990) carried out a radial velocity (Doppler shift of spectral lines) study of the star in April and May 1988, which showed variability with a frequency of the order of a few microhertz, the highest peak corresponding to 4.3 Î¼Hz (2.7 days) with an amplitude of 60 ms-1, with a frequency separation of ~5 <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

deapfreeze · Aug 3, 2007

Of course I am ready. As an added bonus I am off work until Tuesday so I hope to get some viewing in this weekend. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> William ( deapfreeze ) Hooperhttp://deapfreeze-amateur-astronomy.tk/ </div>

derekmcd · Aug 4, 2007

The Milky Way and the Andromeda Galaxies will combine (not collide) in ~3 billion years. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

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