Real time or not?

[Christinea]

As a complete newbie and totally ignorant of all things astrological and celestial, please forgive what to most will be a really stupid question.

When I am looking at the moon is it in real time, as in when I look at my car on the drive for example?

Light years is something that I get the gist of but find hard to translate into something tangible in my mind, other than seeing something on the horizon and although I can see it i know that it will take me a while to get there (if my analogy make any senses at all to anyone else).

Christine

[scotttumsh]

Hi light from the moon takes just over 1.2 seconds to reach us, hope that answers your question. just under a quarter of a million miles away.

[Christinea]

What more proof of my ignorance can there be than my putting astrological instead of astronomical ???!!!

Thank you Scotttumsh. That does answer my question. 

Christine

[ollypenrice]

When watching cricket on the village green you'll see the batsman swing and strike the ball but there will be a delay before you hear the whack, because light travels faster than sound. All information takes time to travel from its source to you, whether by sound, by light, by letter, or however. So no information passes instantaneously from one place to another and 'real time' observation doesn't exist anywhere. The reason this is more obvious in astronomy is simply because of the distances involved.

The sun is about 8 light minutes away. The next star beyond the sun is about four and a quarter light years away. Astronomy is the antidote to claustrophobia...

Olly

[Christinea]

Thank you Olly,

I like the analogy that you have given. That makes sense, even to me.

I had never thought in terms of '...no observation is in 'real time'..' before. By definition I suppose it cant be.

Is a knowledge of light speed essential as part of this interest?

Christine

[ghostdance]

Is a knowledge of light speed essential as part of this interest?

Christine

Don't know about essential, but when you look at, say, Andromeda M31 and realise that  the light you're observing it by left there millions (billions?) of years ago and has travelled that long, as Qualia so memorably described it, to make it into your eyeball....well, certainly adds interest!

And inevitably, I think one picks up all manner of facts and knowledge just by the simple act of stargazing & asking questions!

Grand, aint it

[rowan46]

Thank you Olly,

I like the analogy that you have given. That makes sense, even to me.

I had never thought in terms of '...no observation is in 'real time'..' before. By definition I suppose it cant be.

Is a knowledge of light speed essential as part of this interest?

Christine

only in the sense  that distance is measured  by light years ie the distance light travels in a year if you get interested in physics and cosmology a deeper understanding is involved. I simplify as well as I am not too bright, I look at it in terms of postage. A package is posted eg 12 light years away it arrives on our doorstep 12 years later.( for some reason I can't get the thought of royal mail out of my head)

[Astro Imp]

only in the sense  that distance is measured  by light years ie the distance light travels in a year if you get interested in physics and cosmology a deeper understanding is involved. I simplify as well as I am not too bright, I look at it in terms of postage. A package is posted eg 12 light years away it arrives on our doorstep 12 years later.( for some reason I can't get the thought of royal mail out of my head)

Sounds about right for Royal Mail 

[ollypenrice]

Thank you Olly,

Is a knowledge of light speed essential as part of this interest?

Christine

I'll say 'yes.'

However, it is incredibly simple. Light travels at 300,000 Km per second. That is how long it takes to send a message over 300,000 Km. It takes a second. That might seem fast until you think about how far away things can be in astronomy and measuring things in kilometres really is a bit daft because they aren't long enough! We don't measure the distance between London and New York in millimeters because mm are too small.

It gets more interesting when you read about EInstein's relativity because then you discover that the speed of light is the speed limit for the universe. It cannot be exceeded because, by the time you reach the speed of light, time has stopped. This takes the conversation to another level. When you are up for it, do the reading. You'll love it!

Olly

[Northern Soul man]

Hi Christine and a very warm welcome to the SGL, The Voyager spacecraft took off from Earth in 1977, its been travelling away from the Earth ever since- so the best part of 40 years, its just crossed over the boundary into interstellar space after leaving the Solar System - think of light travelling at the speed of light for a year - a lightyear- After travelling for the best part of 40 years - Voyager is still only 17 Lighthours away from us now - mind blowing.

Paul.