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How big/far

Sam1060

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Sparrow

Sparrow

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Posted

To try and give you an idea to grasp it - if you could bend a light beam round the Earth, it would travel round the Earth about 7 times in one second. (one light second is 186,000 miles).:)

It would travel round the Earh 31,536,000 times in a year.

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Ad Astra

Ad Astra

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Posted

The light year is a simple concept to describe, but not always easy to grasp.

Light travels about 300,000 km per second. (186,000 miles/sec if your are interested!) At that rate, the Moon is about 1.5 seconds away, the Sun is 8 minutes away, Saturn about 1.5 hours away, and Pluto (yes, it IS a planet!) is about 12 hours away.

Our entire solar system is about 1 light-day wide. :) The nearest star system is roughly 4.5 light years away - about 1600 times farther. Trouble is, there are no convienient markers between the two. Solar systems are generally on the scale of light hours or at most light days, while stars (even in dense clusters) are usually separated by many light years - a distance thousands of times greater.

The scale (and emptiness) of the Universe is hard to grasp. A professor of mine built a scale model of the solar system with the Earth as a 1-inch globe. The sun was a 12-ft globe (a yellow dome tent was used as a stand in on campus!), and Jupiter was a 1-ft ball. The model spread across several states. Individual globes were hung in roadside convenience stores and students could get extra credit by taking a journey to 'one of the planets', then photographing yourself in front of the displayed planet - and attaching a reciept from the store! On this scale, Pluto was something like 600 miles away (about a 12-14 hour drive!) Still, even at this scale, (12,000 miles to the inch!) the nearest star would have been 4 times farther away than the Moon!

Hope that helps!

Dan

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Squagnut

Squagnut

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If light-years stretch the imagination beyond comprehension, wait 'til you try the parsec ...

The way I explain why humans have such problems grasping the enormous distances in space is by using human history; we evolved to survive on this lump of wet rock by throwing sticks at cows. Although we have accumulated more knowledge, modern humans are exactly the same creatures as bronze-age humans, and an understanding of interstellar distances is academic - it's not been essential to our survival. This may change, of course.

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ollypenrice

ollypenrice

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Posted

Like many other keen cyclists I've done enough miles, by bike, to get to the moon. A typical club racing cyclist riding non stop at 25mph would, therefore, take a little over a year to get there. I always find that a bit surpising. It's not all that far away. The stars, on the other hand.... uh-oh!

What confuses people about the Lightyear is simply that it is a unit of distance, not of time, despite containing the word 'year.'

Olly

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