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Old 2006-09-15, 18:39   #45
ewmayer
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Quote:
Originally Posted by cheesehead View Post
He proposed it!
Yeah, I saw a note about that in a an article I read later.

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Furthermore, adding to the perfection of Brown's choice,
Quote:
Originally Posted by skytonight.com
The satellite, now called Dysnomia, is named for Eris's daughter, the goddess of lawlessness — a tribute, says Brown, to the actress who played Xena, Warrior Princess: Lucy Lawless.
Ooh, that's good - that's very good. Xena still gets her props via an oblique route ("...Reflecting the obliquity of the object's orbit, Brown said, with an icy stare...") - very nice. Now we just need to figure out a way to sneakily name the next one after Bruce Campbell ("Autolycus" makes for a nice-sounding a nice-sounding astro-name) ... and before anyone in the peanut gallery starts to snicker, consider that the late musician Frank Zappa has an asteroid named after him.

OK, I'm hapy now - thanks for the addtional info, Richard!

Last fiddled with by ewmayer on 2006-09-15 at 18:44
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Old 2006-09-16, 01:51   #46
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Default A matter of definitions

I would have preferred to agree with the redefinitions as:
Pluto-major asteroid as newly defined.Including a definition and word for space orientated C of G.

Current asteroid redefined planetary miniscoid,wherever occuring.
Hence if it turns out there are 16 or 17 major planets and asteroids(with 17 pluto in the middle) we wont have to go through depression to understand
that solids and space interconnect, with yet another definition rehassle.
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Old 2006-10-03, 17:29   #47
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[QUOTE=jinydu;58282]Actually, many scientists do not regard Pluto as a planet; and one reason is that the plane of Pluto's orbit is also inclined relative to the plane of the 8 "surefire" planets. However, this new "planet" is even more inclined.

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Originally Posted by jinydu
I think I know what you're thinking of. Until the last few centuries, only 6 planets were known: Mercury, Venus, Earth, Mars, Jupiter and Saturn.
FYI: Indian astronomers/astrologers had postulated a seventh planet at the time of Christ called Ketu purely because it completed the mystical number 7, and its effects on humans, though they could not and did not observe it.
Such is the power of hypothetical conjecture!
Mally

Last fiddled with by mfgoode on 2006-10-03 at 17:34 Reason: Add on
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Old 2006-10-03, 21:56   #48
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Quote:
Originally Posted by mfgoode View Post
FYI: Indian astronomers/astrologers had postulated a seventh planet at the time of Christ called Ketu purely because it completed the mystical number 7, and its effects on humans, though they could not and did not observe it.
For what it is worth, there are several other suggestions from various places that other cultures may have in fact seen Uranus. It is with in the limits of a sharp eyed person under very good conditions. As are some asteroids on occasion. I recently tried to see an asteroid, how ever I was not able to get to a good dark sky location during the best night.

I personally have seen Uranus with out optical aid a few years ago. In a dark sky location, I used averted vision to see it. It was in the exact right spot as the chart and it had just enough color to not be a star.
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Old 2006-10-04, 16:26   #49
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Originally Posted by Uncwilly View Post
For what it is worth, there are several other ....

I personally have seen Uranus with out optical aid a few years ago. In a dark sky location, I used averted vision to see it. It was in the exact right spot as the chart and it had just enough color to not be a star.

Uncwilly how can you tell a star from a planet by its colour? I always thought that a sure fire way, is to see that a star blinks but a planet doesnt.
Mally
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Old 2006-10-04, 16:51   #50
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Quote:
Originally Posted by mfgoode View Post
I always thought that a sure fire way, is to see that a star blinks but a planet doesnt.
A good rule of thumb, but not "sure fire".

"Blinking" (the technical term is scintillation) is caused by rapidly changing variations in the refractive index of the atmosphere between the source and the observer. Astronomers call these variations "seeing". The effect of the seeing is to change the apparent position of a point source from moment to moment.

If the changes occur more rapidly than the observer can see, the effect of seeing is to blur an image.

If the changes are slow enough, point sources appear to jiggle around and/or change intensity. For point sources, this gives rise to scintillation.

If the changes are slow enough the effect on sources depend on the relative sizes of the seeing, the source and the resolution of the detector. The limiting cases are:

1) source larger than the seeing, seeing smaller than detector resolution. In this case, the source appears blurred and slightly fainter.

2) source larger than the seeing, seeing larger than detector resolution. In this case, the image shows "boiling". You see this effect when looking through the hot air rising above a fire, for instance.

The amount of scintillation depends on the amount of churn in the atmosphere. From very good sites on very good nights the amount of scintillation can be indetectable with the naked eye, even for point sources like stars. On very bad nights, the seeing can be so bad that images of even non-point sources like planets can be moved around and so scintillate. I've experienced both extremes during my sessions of astronomical observing.

Paul
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Old 2006-10-04, 18:13   #51
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Very well explained Paul. I really have learnt something as many times I have experienced the effects you have mentioned in both extremes.

However you have not mentioned the colour of stars and planets and I agree my rule of thumb is not 'sure fire' except for the planet Mars the 'red' planet and Venus the silvery one.

The largest star Betelgeuse (the red giant) in the constellation Orion ? and the dog star Sirius about the brightest in the 'heavens' can also be distinguished by the naked eye.

Are there some other tips you can give as to tell by colour which is which?
Thank you
Mally
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Old 2006-10-04, 21:21   #52
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Originally Posted by mfgoode View Post
However you have not mentioned the colour of stars and planets and I agree my rule of thumb is not 'sure fire' except for the planet Mars the 'red' planet and Venus the silvery one.
Are there some other tips you can give as to tell by colour which is which?
Uranus has blue-green hue to it. Jupiter and Saturn are toward the yellow part of the spectrum, which make them hard to distinguish from 'white' stars. Uranus has more hue than any other greenish object you are likely to see (except meteors.)

It is so faint of an object, that to see it with the unaided eye, one needs to use averted vision. Using a star chart (preferably with the location of the planet marked), find the appropriate area and lock into the stars that are closest. Then, begin to look off to the side. Pay attention to the area of vision off centre. If you are lucky, you will see the area light up with more stars. Dark adapted eyes and dark skies are important to see it. It is not bad to have a tree line blocking the horizon too.
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Old 2006-10-05, 21:41   #53
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Originally Posted by Uncwilly View Post
Uranus has blue-green hue to it. Jupiter and Saturn are toward the yellow part of the spectrum, which make them hard to distinguish from 'white' stars. Uranus has more hue than any other greenish object you are likely to see (except meteors.)
Venus is bright-white, but usually much brighter than any nearby stars. Mercury has a distinct metallic yellow-orange tint. Both of the above are always seen as distinct crescents from earth, and that gives them a somewhat non-stellar aspect, even to the unaided eye, which can't clearly make the crescent out.

On the subject of new extrasolar planets, nice article in today's New York Times:
Quote:
New Planets Astound Astronomers in Speed and Distance
By DENNIS OVERBYE
Published: October 5, 2006

In the quest for other worlds beyond the solar system, astronomers keep turning up planetary systems with curiouser and curiouser traits. Yesterday, astronomers who use the Hubble Space Telescope announced that they had done it again, this time locating the fastest moving and most distant ever found.

Among a batch of new planets found by training the Hubble telescope on a small patch of sky far across the galaxy in Sagittarius are as many as five that orbit their home stars in less than a day.

One planet orbits its star, a so-called dwarf slightly smaller than the Sun, in only 10 hours, “the likes of which we had never seen before,” Kailash Sahu of the Space Telescope Science Institute, leader of the team that did the work, said, calling the results “a big surprise.”

By comparison, Mercury, swiftest in the our solar system, races around the Sun once every 88 days.

The new planets, all roughly the size of Jupiter, orbit so near their stars that they are heated to 3,000 degrees Fahrenheit, said Dr. Sahu, who noted that if their home stars were any bigger, the planets would simply evaporate.

The astronomers reported their results at a news conference at NASA headquarters in Washington, and their findings will be published in the journal Nature today.

The results, astronomers said, confirm that planets occur across the galaxy with the same frequency that they do in the neighborhood around the Sun.

“We’ve learned now that planets are everywhere,” said Alan P. Boss, a theorist at the Carnegie Institution of Washington, who was not part of the team.

“We’re beginning to be able to calculate how many Earths there are, how many planets are habitable, if not inhabited,” Dr. Boss added.

More than 200 planets have now been found around other stars.

In all, the project — known as Sagittarius Window Eclipsing Extrasolar Planet Search, or Sweeps — found 16 possible planets by monitoring the light from 180,000 stars over seven days, looking for the periodic dimming caused by the passage of a planet. The astronomers have calculated by statistical methods that at least seven of the bodies are actually planets.

So far, two have been confirmed as planets by measuring the wobbles in the starlight caused by the passing masses, using the giant eight-meter Very Large Telescope at the European Southern Observatory on Cerro Paranal, in Chile.

Dr. Sahu said those findings gave him confidence that at least a large fraction of the 16, if not all, are really planets.

Dr. Boss noted that astronomers now had found in the Milky Way all the types of planets that are in our solar system: gas giants like Jupiter, ice giants like Neptune and rocky “super-Earths” orbiting other stars. “Everything we were looking for,” he said, “just not in the arrangement we were looking for.”

As potential planets are found in increasing numbers, Dr. Boss said, the odds increase that planets and planetary systems like Earth’s would be found.

Mario Livio, an astronomer at the Space Telescope Science Institute and a member of Dr. Sahu’s team, said, “There are literally billions of planets in our galaxy.”
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Old 2006-10-05, 22:26   #54
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As potential planets are found in increasing numbers, Dr. Boss said, the odds increase that planets and planetary systems like Earth’s would be found.
People seem to be very eager to find and Earth equivalent. I don't understand why that is. I think there must be many ways that life can be formed. Let's not expect all life to be formed like our own. There could be life on some of the small moons around Jupiter, they could be methane based and live underground unseen by our probes. Perhaps these distant planets also have life of "weird and stange" forms that would be truly alien to us in almost everyway.
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Old 2006-10-05, 22:53   #55
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Originally Posted by retina View Post
People seem to be very eager to find and Earth equivalent. I don't understand why that is.
Not wanting to feel like one is all alone (as a species) in an awfully big universe, perhaps? To understand more about the origin and ultimate fate of our own solar system? Natural human curiosity? I don't understand why you don't understand why that would be so, especially on a science/maths-oriented forum such as this, where one could similarly ask:

"People seem to be very eager to find ever-larger prime numbers. Why is that?"

And in the case of the extrasolar planetary systems (unlike that of the primes), you have a combination of both scientific and a deeply human motives. I find it shocking that anyone would *not* be interested in knowing whether there is other intelligent life in the universe. That's probably the second-biggest of the Big Questions, right behind "where did the universe come from and what is its ultimate fate?"
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