Pluto spots?
Hummmm, why are there so many cats on a planet named after a dog? And spot is a dogs name too. Makes you wonder....
WHAT ARE the 'WEIRD' SPOTS seen on far-flung PLUTO?
Astroboffins remain baffled by four mysterious dark spots captured in images buzzed back to Earth from NASA's New Horizons probe as it dashes towards its fateful rendezvous with dwarf planet Pluto. In particular, scientists have been fascinated with the size and spacing of the spots, which face Pluto's largest moon, Charon, …
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Sunday 12th July 2015 20:28 GMT VeganVegan
Re: It's and it's
At the risk of severe down-voting due to excessive pedantry, please take the following as a public service message.
I learnt from my grammar teacher too many years ago that that apostrophe takes the place of a missing letter, often 'i', but can also be 'a'.
Thus:
it's == it is, there's == there is, etc.
Similarly,
they're == they are, we're== we are.
This makes it easy to apply the correct words. When in doubt, ask yourself if it's sensible to say "Pluto and its spots", versus the incorrect "Pluto and it's (==it is) spots".
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Sunday 12th July 2015 23:35 GMT bep
Re: It's and it's
Oh well, at the risk of etc., your grammar teacher should also have explained that apostrophes are also used to indicate possession, as in "Pluto's moon Charon." This applies to Tom's car and Pluto's moon, but it doesn't apply to 'it' for reasons which remain obscure to me but others can no doubt explain. So it's its, not it's after all.
Sorry about that.
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Monday 13th July 2015 01:04 GMT VeganVegan
Re: It's and it's
You are absolutely correct that apostrophe-s is used to indicate possession. The confusion is between the contraction and possession, that the rule of thumb I was taught helps.
The additional source of confusion is that " its " seem strange not to have an apostrophe, even though it indicates possession. The 'explanation', more of another rule of thumb (isn't English marvelous?): possessive pronouns do not use an apostrophe, witness his (his true spots are showing), or hers (those spots are hers), and theirs (the spots are theirs).
And let's not even get started on all the other forms of contractions, like I'd, haven't, could've (the mother of could of), etc..
Some languages are so orderly that one can easily remember the small number of exceptions to the rules. English is one where the number of exceptions just might exceed the number of rules.
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Monday 13th July 2015 08:32 GMT Anonymous Coward
Re: It's and it's
Could've is the *child* of 'could have' but has given birth the abomination 'could of' because that's what 'could've' sounds like in Essex.
On the its / it's / possessives discussion, it's simple: in this case an apostrophe to denote a missing letter trumps a possessive apostrophe - therefore, since both it's (it is) and it's (as a possessive) look identical, there is a tacit rule that it's (as a possessive) becomes its.
It's a pretty straightforward rule with only two outcomes, for a very common word. Learn it, people.
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Monday 13th July 2015 09:09 GMT Yugguy
Re: It's and it's
Could OF annoys the hell out of me.
Noone EVER says "I of had my dinner" yet these days everyone says "I could of had my dinner" because that is what they hear others say - they do not know it is "could've"
This is DIRECTLY related to the lack of grammar tuition in schools. If it was still taught properly they would know that it is simply the contraction of "could have" and that it is ALL just different tenses of the verb "to be".
IMO saying "could of" and "should of" makes you sound stupid and I am determined my own child will not suffer from this.
As for bloody apostrophes, the plural apostrophe is everywhere now, in print, signage, official government communications. We may have lost this battle frankly.
I just wish these morons would be at least consistent in their error. They put the apostrophe in some plurals and not others with no seeming logic as to which.
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Monday 13th July 2015 09:45 GMT Anonymous Coward
Re: It's and it's
Maybe it does not apply to "it" because it would be hard to tell it from "it is" contracted form?
Joke aparts, most ancient indo-european languages used "cases" which inflected the word itself to indicate its grammatical use. While in many modern languages this was lost (but many others still retains them), sometimes it still somehow survives in some basic language words, i.e.. "they" (nominative), "theirs" (genitive), "them" (accusative/dative/ecc.). The possessive 's is still a relic - AFAIK - of Old English genitive case, while other caseless languages fully use prepositions in this situation.
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Monday 13th July 2015 10:40 GMT Wilseus
Re: It's and it's
"your grammar teacher should also have explained that apostrophes are also used to indicate possession"
I vaguely remember reading somewhere that using an apostrophe for possession is in fact a contraction of a construct that is no longer used:
Pluto's moon is a contraction of Pluto its moon.
Similarly, Tom's car is a contraction of Tom his car.
I'm not sure how this would have worked for women though, e.g. Alison's car != Alison her car, perhaps it's a throwback to times when everything belonged to the man of the household!
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Sunday 12th July 2015 15:02 GMT Paul Crawford
That is a lofty goal, but I think the problem of slowing a probe down to get into orbit around a (relatively) light system is going to be a show-stopper in terms of fuel demands (as you have to get the probe+fuel up there and fast enough in the first place).
An atomic powered ion-engine craft might be possible...
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Sunday 12th July 2015 16:26 GMT Chris Miller
Ion-engine
According to the back of this-here envelope:
Distance to Pluto = 7.5 billion km
acceleration of 0.0003 m/s2 (this is what Dawn achieved)
Time to half-way turnover = 3.5 years
So 7 years for a voyage to a stop at Pluto, with peak velocity of 33 km/s.
(All ignoring gravity wells, possible 'slingshot' from intermediate bodies, initial lift to escape velocity &c &c, but order of magnitude should be correct if I haven't slipped a decimal point ...)
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Monday 13th July 2015 08:33 GMT druck
Re: Ion-engine
Well to get the Pu238 for any more RTGs, things will have to get tense enough with Mr Putin in order for the US to restart it's nuclear weapon breeder reactors. Although I suspect the UK might enough in used fuel rods waiting at Sellafield for reprocessing, to kit out a mission or two.
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Monday 13th July 2015 10:06 GMT Anonymous Coward
Re: Ion-engine
How could you measure distance in km/s? It doesn't have the dimension of a length at all.
Unless you pair it with the time within the mission. Sure, maneuver A will happen at T + something, not at X km from point P, just it happens in any system where you can't measure position continuosly and accurately so you need to calculate it based on speed and time. It was called "dead reckoning", and in space works well because effects on speed and course are less "chaotic" than within Earth atmosphere.
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Monday 13th July 2015 21:25 GMT Chris Miller
Δv
It's a tiny rocket scientists' joke - delta-v measures the change in velocity that a given rocket configuration of thrust and fuel is capable of delivering to a specified payload, and that (kinda) defines what you can do with it. A Δv of 8 km/s will get you from the Earth's surface to orbit, for example and 11 km/s (escape velocity) will get you to most places in the solar system, eventually. It doesn't tell you how long it will take to get there - Voyager has accumulated enough Δv (>42 km/s) to reach another stellar system, but it may take some time ...
Wikip article.
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This post has been deleted by its author
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Monday 13th July 2015 03:20 GMT Martin Budden
Re: Polygon
OK, here's a quick discussion. Where convection cells exist within a liquid you'll see polygonal (mostly tending towards hexagonal) surface temperature gradients, with the hotspots at the centre of each cell, cold lines at the boundaries of the cells, and fluid flowing from the central hotspots outwards towards the cold boundaries. See figure 6 on this page. So it's credible that a planet with a once-liquid water layer could freeze and some of that cell structure might still be visible (amazingly, some of the water may even still be liquid below the surface!).
The same process also occurs with thermals in our lower atmosphere, which is why glider pilots like to seek out cumulus (these clouds sit on top of a rising thermal in the middle of a convection cell) and avoid the "blue sink" of clear-sky areas between the cumulus. Sometimes a prevailing wind can cause the cumulus to form near-continuous lines, gliders can use these "cloud streets" to travel long distances.
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Tuesday 14th July 2015 00:45 GMT Martin Budden
Re: Polygon
Basalt columns look very similar but they are caused by contraction fractures when cooling, not by convection cells.
The best basalt columns I've seen personally are at Sawn Rocks in New South Wales, Australia.
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Monday 13th July 2015 18:25 GMT x 7
when we send the next one, why not fit it with bungee cords and grappling hooks so it can get trapped by Pluto and slowed down enough to land. Bit like an aircraft carrier. With no atmosphere you don't need to worry about the probe burning up, so you could use a mile-long bungee tether with a giant treble fish hook on the end, and aim about a quarter of a mile off the surface. Gives plenty of room for error. The probe itself might need blowup bulgarian airbags to absorb the impact of landing, but that technology is simple enough
Biting the hand that feeds IT
