Scale of Earth and Sun Scale of Earth and Sun
Scale of Earth and Sun
⇐ Use this menu to view and help create subtitles for this video in many different languages. You'll probably want to hide YouTube's captions if using these subtitles.
- My goal in this video and the next video is to start
- giving a sense of the scale of (really, just) the Earth
- and the solar system, and as we see as we start getting into
- (like) the galaxy and the universe
- it just becomes almost impossible to imagine
- but we'll at least give our best shot.
- So I think most of us watching this video know
- that this right here is Earth.
- This right here is Earth.
- And just to get a sense of scale here, I think, probably...
- probably, the largest distance that we can somehow relate to...
- is about a hundred miles [ 100 miles ~ 161 km].
- You can get into a car for about an hour, hour and a half
- and go about a hundred miles.
- And on the Earth, that would be about THIS far.
- It would be a speck that would look something like that.
- That is a hundred miles!
- And also to get us a bit of scale,
- let's think about a speed that at least we can kind of comprehend.
- And that would be maybe the speed of a...
- Let's think of the speed of a...
- Bullet. Speed of a bullet.
- Maybe we can't comprehend it.
- But I'll say that this is the fastest thing that we can maybe kind of comprehend.
- It goes about...
- (and there are different types of bullets
- depending on the type of gun and all of that)
- about 280 meters per second,
- which is about 1000 kilometers per hour.
- And this is also roughly the speed of a jet.
- Of a jet...
- So just to give a sense of scale here, the earth's circumference,
- if you were to go around the planet,
- the earth's circumference, just like that, is about 40 000km
- 40 000km...
- So if you were to travel at the speed of a bullet,
- speed of a bullet,
- or the speed of a jet liner, 1000km/h
- it would take you 40 hours to circumnavigate the Earth
- 40 hours to go around the Earth...
- And I think (these) none of these-this information is too surprising
- you might have taken a 12- or 15-hour flight
- that get you, not all the way around the Earth,
- but get you pretty far:
- San Francisco to Australia, or something like that.
- So right now these aren't at scales that are too crazy,
- although (you know), even for me, even the Earth itself is a pretty
- mindblowingly large object.
- Now, (with that out of the way), let's think about
- the Sun.
- Because the Sun starts to approach something far more huge.
- So this, obviously here, is "the Sun".
- And I think most people appreciate that the Sun is larger, that it's MUCH larger than the earth,
- and that it's pretty far away from the Earth,
- but I don't think most people, including myself,
- fully appreciate how large the Sun is, or how far it is away from the Earth.
- So just to give you a sense: (the Earth) the Sun has, the Sun is
- 109*circumference of the Earth!
- Times the circumference of the Earth!
- So if we do that same thought excersise there
- if we said: Ok, if i'm travelling at the speed of a bullet, or the speed of a jet liner,
- it would take me 40 hours to go around the Earth
- well, how long would it take to go around the Sun?
- So if you were to get on a jet plane, and try to go around the Sun,
- or if you were to somehow ride a bullet, and try to go around the Sun
- do a complete circumnavigation of the Sun
- it's going to take you
- 109, times, as long as it would have taken you to do the Earth.
- So it would be 100, times, (I could do 109, but just for approximate)
- it's roughly 100*the circumference of the Earth
- so 100*40=4000
- 4000 hours!
- And just to get a sense of what 4000 is
- actually, since I have the calculator out
- let's do the exact calculation:
- It's 109*the circumference of the Earth
- 109*40 hours
- that's what it would take you to do a circumference of the Earth.
- So it's 4360 hours to circumnavigate the Sun,
- going at the speed of a bullet, or a jet liner!
- And so, that is: (24 hours of the day)
- that is 181 days!
- It would take you roughly half a year
- it would take half a year to go around the Sun, at the speed of a jet liner.
- (let me write this down)
- Half a year!
- half a year...
- The Sun is HUGE!
- The Sun is huge!
- Now, that by itself may or may not be strange
- Actually, let me give you a sense of scale here
- I have this other diagram of a Sun.
- This other diagram of a sun...
- We'll talk more about the rest of the Solar Sytem in the next video.
- But over here, at this scale, the Sun
- the Sun, atleast on my screen, if I were to complete it
- it would be about 20 inches in diameter.
- The Earth is just this little thing over here!
- Smaller, smaller than a raindrop
- it's just this small little thing over here.
- If I were to draw it on this scale, where the Sun is even smaller,
- the Earth would be about that,
- the Earth would be right about that big.
- Now, what isn't obvious, because
- we've all done our science projects in 3rd and 4th grade,
- (or you) we always see these diagrams, of the solar system, that looks something like this:
- Is that the planets are WAY further away
- even though these are (this is) (these are), uhm
- depicted to scale, they are WAY further away from the Sun than this makes it look.
- So the Sun (sorry), the Earth; is 150 million kilometres from the Sun.
- So the Earth, Earth is:
- so this distance, (this is) if this is the Sun right here
- if this was the Sun right here, you wouldn't even
- at this scale, you wouldn't even be able to see the Earth!
- Wouldn't be able to see the Earth...
- It wouldn't even be a pixel.
- But it would be a 150, it would be 150 MILLION
- 150 000 000km from the Earth.
- And this distance right here is called an astronomical unit
- we'll be using that term in the next few videos
- just cause it's an easier way to think about distance.
- Sometimes abbreviated "AU": "Astronomical Unit".
- Astronomical Unit...
- And just to give a sense of how far this is
- light, which is something that we think is almost infinitily fast
- (that, you know) something that looks instantaneous
- THAT takes 8 minutes to travel from the Sun to the Earth!
- If the Sun were to disappear, it would take 8 minutes for that light,
- for us to know, that it disappeared on Earth.
- Or another way, just to put it in the sense of this jet air plane
- let's get the calculator back out
- So we have a hundred, we're talking about 150
- that's thousand, million!
- That's 150 million kilometres.
- So if we're going at 1000km/hour
- going at 1000km/hour, it would take us:
- 150 000 hours, at the speed of a bullet, or the speed of a jet plane
- to get to the Sun, and just to (get) put that in perspective:
- (that) if you wanted it in days: there's 24 hours/day
- so this would be 6250 days, or if you were to divide by 365:
- Roughly 17 years!
- If you were to shoot a bullet straight at the Sun, it would take 17 years to get there!
- If it could maintain it's velocity somehow
- So this would take a bullet or a jet plane 17 YEARS to get to the Sun.
- 17 years...
- Or another way to visualize it:
- This sun right over here looks (on my screen) it has about a 5" or 6" diameter.
- If i were to actually do the scale: This little dot right here,
- this little dot, which is the Earth, this speck
- this speck...
- If I actually wanted to draw this distance at scale,
- I would have to put this speck about 50 feet away from the sun
- 50-60 feet (15-18m) away from the Sun.
- If you were looking at the Solar System,
- and obviously there's other things in the Solar System,
- we'll talk more about them in the next video.
- You wouldn't even notice this speck! Just this little dust thing flying around this Sun.
- (And we) as we go further and further out of this Solar Sytem we're going to see
- even THIS distance starts to become ridiculously small
- Or another way to think about it:
- If the Sun was about this size,
- If the Sun was about this size...
- then this speck, then the Earth on this scale,
- would be about 200 feet (60m) away from it!
- So you could imagine, if you had a football field,
- if you had a football field...
- Let me draw a football field...
- These are the end zones:
- One end zone, another end zone,
- and if you were to stick, something maybe the size of a medicine ball,
- a little bit bigger than a basketball at one end zone,
- this little speck would be a- about 60 yards away or (about) roughly 60 metres away
- (so this little speck) you wouldn't even notice it, on the scale of a football field!
- Something this size.
- Anyway, I'm going to leave you there, hopefully that gives you just
- (eh) starts to blow your mind, when you think about just the scale of the Sun,
- the Earth, and how far the Earth is away from the Sun.
- And then we're going to see even those distances, even those scales
- are super small when you start thinking about the rest of the Solar System,
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?
Have something that's not a question about this content?
This discussion area is not meant for answering homework questions.
Share a tip
When naming a variable, it is okay to use most letters, but some are reserved, like 'e', which represents the value 2.7831...
Have something that's not a tip or feedback about this content?
This discussion area is not meant for answering homework questions.
Discuss the site
For general discussions about Khan Academy, visit our Reddit discussion page.
Flag inappropriate posts
Here are posts to avoid making. If you do encounter them, flag them for attention from our Guardians.
- disrespectful or offensive
- an advertisement
- low quality
- not about the video topic
- soliciting votes or seeking badges
- a homework question
- a duplicate answer
- repeatedly making the same post
- a tip or feedback in Questions
- a question in Tips & Feedback
- an answer that should be its own question
about the site