Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Scale and facts

observing
  • Please log in to reply
17 replies to this topic

#1 big eye

big eye

    Vostok 1

  • -----
  • topic starter
  • Posts: 137
  • Joined: 13 Nov 2020

Posted 24 November 2020 - 09:32 AM

Get your head around this. The temperature and distance of Alpha Centauri is the equivalent of a powerful 6-inch diameter spotlight at a distance of 3000 miles WOW. Share some scale and facts with us.



#2 Couder

Couder

    Viking 1

  • *****
  • Posts: 738
  • Joined: 24 Feb 2014
  • Loc: Mansfield, Missouri in the Ozarks

Posted 24 November 2020 - 09:42 AM

Each of us is insignificant when looking at the or compared to the Universe, but then we are the ones doing the looking.


  • erin, mikemarotta and big eye like this

#3 Gipht

Gipht

    Mercury-Atlas

  • *****
  • Posts: 2,596
  • Joined: 12 Nov 2016
  • Loc: Prescott Valley, AZ.

Posted 24 November 2020 - 10:02 AM

There could be 5 billion habitable planets in the Milky Way.



#4 big eye

big eye

    Vostok 1

  • -----
  • topic starter
  • Posts: 137
  • Joined: 13 Nov 2020

Posted 24 November 2020 - 10:07 AM

There could be 5 billion habitable planets in the Milky Way.

And there might only be one inhabited?



#5 Steve OK

Steve OK

    Surveyor 1

  • -----
  • Posts: 1,738
  • Joined: 22 Sep 2007
  • Loc: OKC, OK

Posted 24 November 2020 - 11:20 AM

On a scale in which the distance between Earth and the Moon were reduced to the thickness of a sheet of paper, the Sun would be an inch away, and a light year would be a mile.  The nearest star would be 4.6 miles away.  So far, humans have traversed the thickness of a sheet of paper.

 

Steve


  • DeanS, viewer, VeraZwicky and 3 others like this

#6 big eye

big eye

    Vostok 1

  • -----
  • topic starter
  • Posts: 137
  • Joined: 13 Nov 2020

Posted 24 November 2020 - 11:31 AM

On a scale in which the distance between Earth and the Moon were reduced to the thickness of a sheet of paper, the Sun would be an inch away, and a light year would be a mile.  The nearest star would be 4.6 miles away.  So far, humans have traversed the thickness of a sheet of paper.

 

Steve

And on that scale one mile = one light year.



#7 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 95,076
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 24 November 2020 - 11:56 AM

There are 1,625,000 grains of salt in a typical 26oz package of Morton's Salt. To account for all the stars in the Milky Way, one would have to purchase approximately 18,462 boxes of salt.  One bathtub filled with Morton's table salt will hold about 1 billion grains of salt so approximately 300 bathtubs full of salt would be needed. No two grains of salt can be any closer than seven miles to each other. The model will fit into the area encompassed by Mercury's orbit around the Sun.


  • Tom Polakis, mkothe, Steve OK and 6 others like this

#8 big eye

big eye

    Vostok 1

  • -----
  • topic starter
  • Posts: 137
  • Joined: 13 Nov 2020

Posted 24 November 2020 - 12:02 PM

There are 1,625,000 grains of salt in a typical 26oz package of Morton's Salt. To account for all the stars in the Milky Way, we would have to purchase approximately 18,462 boxes of salt.  One bathtub filled with Morton's table salt will hold about 1 billion grains of salt so approximately 300 bathtubs full of salt would be needed. No two grains of salt can be any closer than seven miles to each other. The model will fit into the area encompassed by Mercury's orbit around the Sun.

This would be like 1 billion atoms spread out on a football field.



#9 Gregrox

Gregrox

    Explorer 1

  • -----
  • Posts: 78
  • Joined: 14 Oct 2020
  • Loc: Peidmont Triad in NC

Posted 24 November 2020 - 07:08 PM

"If an apple were magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple."


  • Dave Mitsky, Steve OK, Voyager 3 and 1 other like this

#10 Tony Flanders

Tony Flanders

    Hubble

  • *****
  • Posts: 19,159
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 25 November 2020 - 10:58 AM

If Earth was at the center of the Sun (and didn't evaporate), the Moon's orbit would fit inside the Sun with ample room to spare.


  • viewer and Voyager 3 like this

#11 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 95,076
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 25 November 2020 - 12:16 PM

Let the Earth be represented by a peppercorn with a diameter of 0.08 inch.  One inch would then equal 100,000 miles (160,934 kilometers) in this model.  The distance from the Sun, which would be the size of a bowling ball, to the Earth would be 26 yards (24 meters) and the average distance from the Sun to Pluto would be about 1,109 yards (932 meters).  The distance from the Sun to Proxima Centauri would be approximately 4,000 miles (6,437 kilometers).

https://www.noao.edu...orn/pcmain.html

 


  • DSOGabe and Voyager 3 like this

#12 beatlejuice

beatlejuice

    Mercury-Atlas

  • *****
  • Posts: 2,719
  • Joined: 05 Apr 2011
  • Loc: Hamilton, ON,Canada

Posted 25 November 2020 - 02:37 PM

If an atom were blown up to the size of a football field the nucleus would look like a pea at midfield with the electrons buzzing around the outer reaches of the stands. We are all empty-headedgrin.gif 

 

Eric



#13 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 95,076
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 25 November 2020 - 07:12 PM

Snapple cap fact #206

Attached Thumbnails

  • Snapple Cap.jpg

  • Voyager 3 likes this

#14 russell23

russell23

    Voyager 1

  • *****
  • Posts: 11,470
  • Joined: 31 May 2009
  • Loc: Upstate NY

Posted 25 November 2020 - 11:52 PM

Here is an interesting one which should make sense: an Earth composition planet (~1/3 Fe and 2/3 silicates by mass) cannot have the same density as the Earth unless it has a mass close to the Earth’s.   As planet mass increases, density increases for a given composition.  The Earth’s density is 5.51 g/cm^3.   Using published mass-radius models here are some examples:

 

2.0 Earth mass  & composition planet would have a radius of 1.22 Earth radii and a density of 6.07

 

8.0 Earth mass & and composition planet would have a radius of 1.75 Earth radii and a density of 8.23

 

One of the most massive Earth-like composition planets is Kepler 131b which has a mass of 16.13 Earth masses and a radius of 2.1 Earth radii.  This puts it on the 20% Fe and 80% silicates composition line - so a little less iron rich than Earth.  But its density is 9.61 g/cm^3

 

So watch out for density when you see reports on exoplanet discoveries.  An Earth density does not mean an Earth composition.  As an example, there is K2-180b:  Mass = 11.45 Earth, Radius = 2.24 Earth, Density = 5.61 which is close to Earth’s density.  However, it falls close to the 25% H2O and 75% silicates/iron composition line on the Mass-Radius relation so decidedly un-Earth like.  

 

Perhaps K2-180b is more Ganymede-like in composition.  However, one recent paper showed that these super-Earth to Neptune mass exoplanets with a Ganymede-like composition will not have the separate rock and water layers in the interior.  At the pressure/temperature conditions inside these massive planets the rock and water are >99% miscible and therefore the interior may have density gradients but not distinct layers of different composition as is seen in the icy Satellite planets of the Solar System.  The water and rock in these planets will be fully mixed.

 

Anyway, the point is, in terms of scale, that for a given composition, density increases with planet mass.   So an Earth density planet will not be Earth-like in composition if it has a significantly different mass.  


Edited by russell23, 25 November 2020 - 11:55 PM.

  • Voyager 3 likes this

#15 Bill Weir

Bill Weir

    Mercury-Atlas

  • *****
  • Posts: 2,763
  • Joined: 01 Jun 2004
  • Loc: Metchosin (Victoria), Canada

Posted 26 November 2020 - 01:43 AM

The temperature of the core of Earth is approximately the same as the surface of the Sun.

 

Bill 



#16 ButterFly

ButterFly

    Surveyor 1

  • *****
  • Posts: 1,564
  • Joined: 07 Sep 2018

Posted 26 November 2020 - 06:31 AM

1) Degenerate stars (white dwarfs, neutron stars) get smaller the more mass you add.

 

2) The surface gravity at the event horizon of [non-rotating] supermassive black holes is much much less than that of stellar sized black holes.

 

And, 3) one of my favorite WikiMedia pictures:

 

Star-sizes.jpg


Edited by ButterFly, 26 November 2020 - 06:38 AM.

  • oldmanrick, RobertMaples, DSOGabe and 1 other like this

#17 MajorTom2017#

MajorTom2017#

    Sputnik

  • -----
  • Posts: 46
  • Joined: 11 Sep 2017
  • Loc: Eastern Iowa, USA

Posted 01 December 2020 - 03:44 PM

The cameras in the Kepler Space Telescope have to be incredibly sensitive to see the dimming of a star during a planet transit. It can "see" a light reduction of about 20 parts per million. This is equivalent to seeing a flea pass in front of a car head light at a distance of several miles away.



#18 MajorTom2017#

MajorTom2017#

    Sputnik

  • -----
  • Posts: 46
  • Joined: 11 Sep 2017
  • Loc: Eastern Iowa, USA

Posted 01 December 2020 - 03:58 PM

I believe it was Carl Sagan (or maybe Stephen Hawking) who said with every breath you take you probably inhale at lease one atom from Julius Caesar's last breath as he exclaimed "Et tu Brute?" 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: observing



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics