Space & Science

[Jason Thompson]

*bangs head on desk*

[Paul Monk]

That would actually be quite cool. Especially if they could do a Google Earth type thing. They could run a competion to find some of the golf balls that were left there!

[Jason Thompson]

That would actually be quite cool. Especially if they could do a Google Earth type thing. They could run a competion to find some of the golf balls that were left there!

Don't get overexcited. The resolution isn't that good.

[Zbigniev Hamson]

Golf balls actually contain air at high pressure so that they react well to the impact of a club, but still remain spherical. If left unattended in a vacuum for 40 years, it's concievable that they may expand to the size of a lunar rover.

[WhiteCrowNZ]

Could a mod move this to the I Need You Mr Smith area (it predates that areas creation I know)? I knew we had one, took a bit of time to find this.

Anyway - saw this interesting featured article on Wikipedia today on Ceres - I always thought it was just an asteroid, now classed as a dwarf planet ...

http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

Ceres, formally designated 1 Ceres, is the smallest identified dwarf planet in the Solar System and the only one in the asteroid belt. It was discovered on 1 January 1801, by Giuseppe Piazzi,[17] and for half a century it was classified as the eighth planet. It is named after Ceres, the Roman goddess of growing plants, the harvest, and motherly love.

With a diameter of about 950 km (590 mi), Ceres is by far the largest and most massive body in the asteroid belt, and contains a third (32%) of the belt's total mass.[18][19] Recent observations have revealed that it is spherical, unlike the irregular shapes of smaller bodies with lower gravity.[11] The surface of Ceres is probably made of a mixture of water ice and various hydrated minerals like carbonates and clays. Ceres appears to be differentiated into a rocky core and ice mantle. It may harbour an ocean of liquid water underneath its surface

[Jason Thompson]

Yes indeed. Reclassified around the same time as Pluto, when the IAU decided to sit down and work out how to define a planet. The discovery of many Kuiper Belt Objects, some larger than Pluto, meant that the accepted version of the solar system with 9 planets was no longer acceptable. After all, if Pluto is a planet, so must Sedna, Eris and other bodies be. However, Pluto never sat well in the solar system anyway, with its highly eliptical and inclined orbit, and so the classification 'dwarf planet' came to be. Under that definition Ceres qualified as a dwarf planet.

The situation with Pluto and the Kuiper Belt is very similar to that with Ceres and the asteroid belt, in that the first discovered memebr was considered a planet initially until it was discovered to be one of a large population of similar objects that were in many ways quite different from the major planets.

[Zbigniev Hamson]

Rose by any other name etc

[Jason Thompson]

To a degree, yes, because Ceres is still a small-ish lump of rock orbiting between mars and Jupiter whever we call it, but you know how we humans like to categorise things.

[Zbigniev Hamson]

I'm going to call it a cake.

[WhiteCrowNZ]

It is getting increasingly difficult when we look through and find more and more in the space around us to classify objects in our vicinity.

Obviously the ancients just noticed lights in the heavens which moved differently to others.

But for us - planets like Mars and Venus are nothing like Saturn. If Mecury is a planet, then what makes the Moon not a planet?

And even before Pluto was relegated from planet status, I had a lecturer on my astronomy course who thought Jupiter should be removed from the list of planets, as it is closer to a Brown Dwarf star (it actually radiates more energy than it receives).

[Zbigniev Hamson]

We should just call free-falling objects bigger than individual molecules "astercometplanetars of varying sizes" and avoid all confusion. Apart from all the confusion it would cause of course.

[Jason Thompson]

If Mecury is a planet, then what makes the Moon not a planet?

Primarily it's the fact that the Moon's primary is another planet, not a star. A planet, according to the IAU definition, must be:

Orbiting a star;

Large enough for its gravity to have pulled it into a sphere;

Have cleared its orbit of debris.

The 8 planets all qualify, but the dwarf planets only meet the first two criteria, since they all share their orbits with large numbers of other objects.

And even before Pluto was relegated from planet status, I had a lecturer on my astronomy course who thought Jupiter should be removed from the list of planets, as it is closer to a Brown Dwarf star (it actually radiates more energy than it receives).

Again, the IAU definition requires a mass high enough to fuse deuterium in order to qualify as a brown dwarf. Jupiter is not alone in radiating more energy than it receives. All the giant planets except Uranus do it.

[Stuart Wallis]

And I'd always understood that another difference between a star and a gas giant - one that differentiated between star and planet in this case - was that the star was burning off its gas.

[MinaHarker]

And I'd always understood that another difference between a star and a gas giant - one that differentiated between star and planet in this case - was that the star was burning off its gas.

The definition is that stars have nuclear fusion going on inside them, planets don't.

[Stuart Wallis]

Well that settles that then.

[WhiteCrowNZ]

The great thing about science is you say something with certainty, and soon after a new discovery muddies the water.

From todays Stuff - the Kepler telescope has found some new planets including some objects which are not quite planets, and not quite stars ...

http://www.stuff.co.nz/world/america...ts-and-mystery

[Jason Thompson]

Well, science is no different from anything else, in that it can only operate with available information. Unfortunately many people seem to find fault with science precisely because it updates itself all the time as new discoveries are made, claiming that since it was obviously wrong before it must be wrong all the time and is therefore unreliable.

[MinaHarker]

The great thing about science is you say something with certainty, and soon after a new discovery muddies the water.

From todays Stuff - the Kepler telescope has found some new planets including some objects which are not quite planets, and not quite stars ...

http://www.stuff.co.nz/world/america...ts-and-mystery

I read the article. They are definitely planets, albeit hot ones.

[WhiteCrowNZ]

Well, science is no different from anything else, in that it can only operate with available information. Unfortunately many people seem to find fault with science precisely because it updates itself all the time as new discoveries are made, claiming that since it was obviously wrong before it must be wrong all the time and is therefore unreliable.

I think usually it's more a case of we "discover" more and have to evolve our models to accomodate the new information. It's kind of scary really considering the tools he had to work with how spot on Newtons theory of gravitation was for instance.

I think it is the difference I noticed though between an engineer and science degree. Engineering seems to be this is how you calculate this - all current models. But a science course will often cover all old theories, and cover how they were disproved before moving on to the current theories. So my astronomy course covered how the Greeks viewed the heavens, the subluminous ether and volcanoes on the Moon.

[Jason Thompson]

Engineering seems to be this is how you calculate this - all current models. But a science course will often cover all old theories, and cover how they were disproved before moving on to the current theories.

That's a question of application, surely? When learning engineering you want to learn how to do things now and apply that knowledge now for immediate practical application. When learning science it is important to understand not just the current theories but how they were arrived at, in order to build on that to expand and continue the science.

[WhiteCrowNZ]

Its just an observation I made, as I did take a few Electrical Engineering classes during my post-grad years as I kind of drifted from Astronomy & Physics -> Applied Physics -> Electrical Engineering -> Software Engineering.

You are bang on, when someone used to ask me to create a software program with my "engineer" hat on, I didn't then proceed to give them a history of software development before commencing. Although it would often happen from some geek somewhere "did you know in the early days of programing they used single character variable names to save memory" - how those days just flew by.

Science and Engineering are two very close disciplines, sharing much the same knowledge, but with slightly different approaches to that knowledge.

[WhiteCrowNZ]

Wikipedias article of the day is on Ganymede ...

http://en.wikipedia.org/wiki/Ganymede_%28moon%29

Something I didn't know. The Moon is tidally locked to the Earth, meaning the same side always faces the Earth. But so are most satellites around their parent bodies ...

http://en.wikipedia.org/wiki/Tidal_locking

[MinaHarker]

Tidal locking is very common. The Moon isn't quite perfectly locked to the Earth - yet. A phenomenon called "libration" means we get to see about 55% of the Moon's surface.

[Jason Thompson]

Tidal locking also works both ways. Pluto and Charon are tidally locked to each other, so anyone on one side of Pluto would never even know Charon existed. I think (and Emma will correct me if I'm wrong) that the Sun will die before the Moon and Earth get completely locked with each other, though Earth's rotation is slowing down.

And those regions of the Moon we only see due to libration are also the only places on the Moon where you would ever see an Earthrise.

[WhiteCrowNZ]

I did know the Moon was tidally locked to the Earth, but was surprised how common it is. But then a good deal more has been seen of the Solar System since my first degree (which would have been off the Voyager fly-bys).

Also found this whilst digging around ...

http://en.wikipedia.org/wiki/Europa_...System_Mission

Sounds an exciting mission, although I suspect it will fall victem of funding, and moved back several years from it's 2020 launch.