SultanOfSwing

Most of those objects aren't on a collision course with Earth, it is debris that the Earth moves through in its orbit, some of which get into the atmosphere producing shooting stars or meteor showers, like the Leonids.

Encountering random larger objects like near Earth asteroids, or long-period comets is all about timing. 99.9999% of the time, everything misses because their trajectories have to be 100% perfectly intersecting to result in an impact.

sir_eccles

As Douglas Adams wrote "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space."

The earth is very very small in comparison to all the empty bits around it, so the odds that something would hit the earth are quite small. Unless of course you're in the path of the hyperspace bypass...

SultanOfSwing

One of the best lines came early on in that book, when talking about the Vogon fleet when it first appeared 'The ships hung in the sky in much the same way that bricks don't.' I always liked that one

Anyway, back to spacey stuff, the Juno probe is due to reach Jupiter on July 4. Hopefully it will send back information to rival the absolutely wonderful data New Horizons returned from Pluto.

https://www.nasa.gov/mission_pages/juno/main/index.html

Shard

I've read Douglas Adams (years ago) and often see him quoted (as here) but I genuinely can't fathom why people find him so amusing. Mildly amusing yes, but no more. I did like the 42, that was highly original, but the rest, just a bit droll.

chawkins99

My favourite H2G2 line:

"anyone who is capable of getting themselves made President should on no account be allowed to do the job."

So true.

SultanOfSwing

I don't know why I enjoyed the Hitch Hiker's Guide books so much, but I have reread them more than any of my other books.

Pulaski

I was reading fairly recently that the common misperception of the relative size of planets and the solar system is caused by the composite images of several planets in the same picture, perhaps with the sun in the distance. In order to make such images possible the planets are massively exaggerated in size relative to the distances between them.

I recall a comparison of something like the solar system if reduced to the size of a soccer field, the sun on the centre spot would be a hazel nut, and the "gas giants" would be around the size of a grain of rice. The earth would be a crystal of table salt, and obviously Venus, Mercury, Mars, and Pluto much smaller still.

SultanOfSwing

Those composites vastly underrepresent how much of the solar system is just empty space.

The Sun is 98% of the mass of the solar system, the orbit of Neptune is just short of 3 billion miles in diameter and the Oort cloud theoretically extends to a diameter of a light year. That's a lot of nothing in between ...

Shard

Just looked this relative scale up. Sun would be a 50" umbrella, earth a mini marshmallow and Saturn a grapefruit.

Pulaski

And yet the Sun is a fairly insignificant star and one of billions of stars in the milky way, which in turn is only one of billions of galaxies.

That all rather puts things in perspective, doesn't it.

sir_eccles

To quote Carl Sagan "Billyuns and billyuns"

Yet here we are arguing over the relative merits of top loaders v front loaders.

steveq

There has to be an obligatory Python quote.

Pulaski

I thought we had agreed, front loaders are obviously better.

Nutek

SultanOfSwing

Hundreds of billions

But yeah, the sun is bang average and now we're discovering more and more exoplanets it appears that stars having planetary systems are bang average as well, which means for every billion stars, there could be maybe three billion planets, adjusting for stars that might not have any.

Yet there's still way more empty space between the matter than there is matter itself.

I agreed that I didn't care, but I'll admit I was an outlier on that one.