Author Topic: Ask an astronomer  (Read 43628 times)

starsmurf

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Ask an astronomer
« on: July 25, 2013, 04:54:35 PM »
I hope people don't think this is vain but I thought I'd start a thread inviting people to ask me anything they'd like to know about astronomy or space.  I wanted to start a thread because I know sometimes people may be curious but feel it would be rude or intrusive to ask questions.

When people find out that I'm an astrophysicist (I'm technically both astronomer and astrophysicist), they always want to ask me questions on astronomy and space.  That's how I spent New Year's Eve 1999, I think the malt whisky helped people overcome their reserve!  I've even given talks to enclosed nuns and then had a question and answer session.  I nearly collapsed at the first talk when I found out that one Sister's cousin had won the Nobel Prize in Physics.  She wanted a copy of the talk, which I gave her with strict instructions not to show it to her cousin!  >lol<

There is no such thing as a stupid question in astronomy, so don't worry that your question is silly or too basic.  I really mean that.  The question "why is the sky dark at night?" led to the discovery of the Big Bang and the fact that our universe is expanding.  There are only stupid answers, from me  >biggrin<
« Last Edit: February 11, 2014, 11:53:26 PM by SunshineMeadows »
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oldtone27

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Re: Ask an astronomer
« Reply #1 on: July 25, 2013, 05:46:55 PM »
I'm glad you have started this thread. I have a passing interest in astronomy largely because I have always been interested in how things work. Not in any great depth (too much for my brain no doubt) but out of curiosity.

I was sad when Patrick Moore died because I found his explanations understandable and satisfyingly detailed without being too complicated. I am afraid Chris Lintoff (is it?) may be knowledgeable but is too dull. There is a black lady astronomer (forget her name), who sometimes appears on Breakfast TV, who is enthusiastic and engaging and I think would be ideal to take over the programme.

To satisfy my curiosity I read the New Scientist regularly as that seems to pitch its articles at about my level of comprehension. No questions at present but now you have asked I sure I'll have some before long.

devine63

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Re: Ask an astronomer
« Reply #2 on: July 25, 2013, 05:58:23 PM »
good idea

why does it matter whether Pluto is a planet or not?
regards, Deb
regards, Deb

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starsmurf

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Re: Ask an astronomer
« Reply #3 on: July 25, 2013, 08:09:12 PM »
good idea

why does it matter whether Pluto is a planet or not?
regards, Deb

I'll put a short answer here and then a longer answer that goes into detail, so that you can decide which you want!  Pluto's planetary status was important because calling something that small a planet, would allow lots of planets in the Solar System.  Another reason it was important was because it was the only planet discovered in the USA and by an American.  ;-)



Pluto's status as a planet was debated for years.  At first, demotion was suggested because of Pluto's size.  It's tiny, only 1441 miles across and has just 0.22% of the Earth's mass.  For comparison our Moon is 2171 miles across and has 1.23% of the Earth's mass.  Pluto is also smaller than 6 moons orbiting other planets (moons orbiting other planets are properly called satellites, Moon is actually the name of Earth's satellite).

The issue became more urgent because of discoveries of other objects out near Pluto (over 40 times further from the Sun than the Earth).  They're part of what's called the Kuiper Belt, it's where the comets that orbit the sun regularly come from.  The Kuiper Belt also contains objects of varying size from the size of a tiny asteroid to over 1000 miles across.  They're the leftover rubble from the formation of the planets and were pushed out there by a planetary dance between Jupiter and Saturn. 

These Kuiper Belt objects were almost the same size as Pluto and it was only a matter of time before an object larger than Pluto would be discovered.  It would then have to be classified as a planet.  As there could easily be tens objects that size, the Solar System could end up with 50 planets, 40 of them smaller than our Moon. In January 2005, an object that appeared to be bigger than Pluto was discovered.  You might have heard about it in the news because it was nicknamed 'Xena', as in "Warrior Princess".

Pluto was reclassifed at the 2006 meeting of the International Astronomical Union, which is the only body with the power to name planets, moons, stars and galaxies, plus any feature on them eg craters or mountains on a planet.  The vote was contentious because it took place in the afternoon session on the last day of the conference, when many members had already had to leave to catch flights etc.

As a kind of "runner-up prize", Pluto, Ceres (the largest asteroid at 900 miles across) Makemake, Haumea (both Kuiper Belt objects) and 'Xena' were defined as dwarf planets. Dwarf planets are objects large enough to have a rounded shape but which aren't large enough to clear out their orbits.

'Xena' was given its proper name by the International Astronomical Union.  It's called Eris, after the Greek goddess of strife, chaos and discord!  >biggrin<
« Last Edit: July 25, 2013, 08:13:18 PM by starsmurf »
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Robuk1981

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Re: Ask an astronomer
« Reply #4 on: July 25, 2013, 09:07:29 PM »
I love looking at the sky due to those modern white lamps I see very little of it. I used to love taking a short cut through my high school on a winters night going home as I was a nice pitch black bubble and caught a few shooting stars over the years.

I have a telescope good enough to see craters on the moon and see Jupiter but I've never managed to find it yet.

I thought our moons name was Luna as in Lunar eclipse etc. And out star Sol as in Solar etc etc
« Last Edit: July 25, 2013, 09:10:12 PM by Robuk1981 »

starsmurf

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Re: Ask an astronomer
« Reply #5 on: July 25, 2013, 10:13:05 PM »
Sol and Luna are sometimes used in popular astronomy articles but the International Astronomy Union refers to them as Sun and Moon, so they're the offical names. Sun and Moon are used in professional astronomy and in astrophysics.  Most English-speaking amateur astronomers would use Sun and Moon too. 

I've heard Luna used for the impactor that struck the Earth in the final stage of planet building, so using Sun and Moon means that there's no confusion about what object you're referring to.
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Hurtyback

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Re: Ask an astronomer
« Reply #6 on: July 25, 2013, 10:31:34 PM »
Now that Pluto has been downgraded it makes a nonsense of my mnemonic - my very easy method just speeds up naming planets  >biggrin<

starsmurf

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Re: Ask an astronomer
« Reply #7 on: July 25, 2013, 10:34:19 PM »
I'm glad you have started this thread. I have a passing interest in astronomy largely because I have always been interested in how things work. Not in any great depth (too much for my brain no doubt) but out of curiosity.

I was sad when Patrick Moore died because I found his explanations understandable and satisfyingly detailed without being too complicated. I am afraid Chris Lintoff (is it?) may be knowledgeable but is too dull. There is a black lady astronomer (forget her name), who sometimes appears on Breakfast TV, who is enthusiastic and engaging and I think would be ideal to take over the programme.

To satisfy my curiosity I read the New Scientist regularly as that seems to pitch its articles at about my level of comprehension. No questions at present but now you have asked I sure I'll have some before long.

Patrick Moore was great at helping people understand astronomy and share his wonder and excitement.  Chris Lintott does well but was intended as a kind of "roving reporter" once Patrick Moore was unable to travel.  I love Dr Maggie Aderin-Pocock, the woman you're thinking of.

There are popular astronomy magazines, which always have sections for beginners.  If you can understand New Scientist you're more than capable of understanding them.  You don't have to go out and stargaze, you can sit at home and just read about the wonders of the universe!
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starsmurf

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Re: Ask an astronomer
« Reply #8 on: July 25, 2013, 10:37:06 PM »
Now that Pluto has been downgraded it makes a nonsense of my mnemonic - my very easy method just speeds up naming planets  >biggrin<

I used to use Most Volcanoes Erupt Moldy Jam Sandwiches Under Normal Pressure.  Now you can use Most Vultures Eat Messily, Just Some Use Napkins.
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Hurtyback

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Re: Ask an astronomer
« Reply #9 on: July 25, 2013, 10:39:35 PM »
How about - my very early morning jam sandwiches often nauseate (people)? The thing I liked about the other one is that it clearly states what it is doing, so I found it easier to remember.

starsmurf

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Re: Ask an astronomer
« Reply #10 on: July 26, 2013, 12:03:58 AM »
The vultures one is good for astronomers as it seperates the two main types of planets, terrestrial (Earthlike, small and rocky) and Jovian (Like Jupiter, big with huge atmospheres).
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devine63

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Re: Ask an astronomer
« Reply #11 on: July 26, 2013, 01:01:30 AM »
thanks Starsmurf, helpful answer.

Can you recommend a couple of websites with good solar system pictures please?

Was there a theory at one point that the Kuyper Belt (then called something else but can't bring it to mind right now) was an exploded planet?   

And have you read Robert Heinlein's sci fi novels, many of which incorporate bits of physics and astronomy?

regards, Deb
regards, Deb

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bulekingfisher

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Re: Ask an astronomer
« Reply #12 on: July 26, 2013, 08:58:33 AM »
Hello Oldtone27

In google search put the words space daily express  or space.com I hope these will help

bubble

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Re: Ask an astronomer
« Reply #13 on: July 26, 2013, 09:04:18 AM »
Hi Starsmurf I love this thread..................

Ive always loved looking at the stars planets they fascinate me. Hubby and me have sat out in the winter with the chiminea lit just watching the sky, how the earth moves and over days the stars are in a different place its all a wonder to me makes me feels quite small.

One thing Ive never got to understand no matter how many times hubby and son try, is the solar system.

how the moon travels around us, and eclipses, i know the moon sun etc all get in front of each other but no idea how.

oldtone27

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Re: Ask an astronomer
« Reply #14 on: July 26, 2013, 10:30:55 AM »
Starsmurf, thanks for the advice about the other mags. I have browsed some on the bookshelves but I like the New Scientist because it covers other sciences as well. It has an article this week about a supernova that is causing astronomers to re-think their theories.

I love it when that happens. Experts having to re-evaluate long cherished theories which have started to become dogma rather than beliefs based on evidence so far.

Bule, thanks for the suggestions I will look them up later.