Astronomical distances: How do we know how far away galaxies are?

[@edmizzimizzi]

Great lesson, thank you

[@mattypusplatypus3340]

Don't take this wrong, but for a while now I've been thinking 'How hard can astronomy actually be? I mean, it's all circles (ellipses)!' No trigonometry in sight, you see. Well, I've just been taken down a peg by a man who has been dead for over two-thousand years. On the plus side, what an amazing insight to calculate the Earth-Sun distance using a simple right-angle, in ancient times no less. More cool stuff to learn, thanks again Dr Lieu! 😊

[@SpaceMog]

Thanks - i know right! I feel like all the simple discoveries have been made and its so hard to make ground breaking science but then they keep coming 😅

[@mattypusplatypus3340]

@@SpaceMog Yeah, that's what always surprises me! I felt like everything moved so slow when I was growing up but now it all moves so fast. I'm not sure if that's just down to better access to information a.k.a the Internet or if we're just discovering things faster. Either way I think I might be getting old lol 😑

[@kenzieplayz9692]

This is the best KZbin Channel

[@SpaceMog]

you're such as sweet heart. Thank you 😘

[@IBHunter]

A little less accurate, but HAM radio operators bounce radio signals off the moon and can measure its distance pretty accurately. Radar was also used to get Venus’s distance so the distance to the sun could be accurately measured. Great video! The background image of the Veil Nebula was great! Thanks!

[@SpaceMog]

Yes, you're correct! There are many ways that we can measure the distance to the moon and this definitely wasn't the first measurement, but the lunar laser ranging experiment offered one of first most accurate readings! The first measurement of the sun was done with the moon, but it wasn't very accurate, later measurements using Venus, didn't require Venus' distance, as long as you know Venus-Sun distance, which you can get from keplar's 3rd law. But you're right now, we know Venus' distance accurately which makes things easier :-)

[@mballer]

I guess that applies to any of the probes sent to the sun or Mars or Pluto or any planet, the time delay of the return signal can always be measured.

[@IBHunter]

M Ball the distance to the sun can be measured many ways. Spotting a CME through a telescope, measure the time until the particles get here, the measure how fast they are traveling.

[@stevegovea1]

Awesome educational channel.

[@SpaceMog]

Thank you 😍

[@yasminaeberhardt2295]

My question is a somewhat related to the topic, I hope I articulate it well enough. In the distant future when other galaxies will no longer be visible due to the expansion of the universe, will astronomers in any galaxy be able to find evidence of the origins of the universe? Will the CMB radiation also redshift and eventually disappear? For any observer in the that distant future, would the only conclusion be that the universe has always existed and only consists of the several hundred billion stars that they can observe or is there other evidence that would point them to discovering the big bang?

[@ABCXYZ-hw1nk]

😮 uff

[@mohamedkorayem6551]

Thanks for ur effort really search many videos and yours gave me the answers am looking for 👌

[@DavidJohnson-pv7sl]

I'm just hooked with how cute of an accent you have, while also being able to learn cool stuff. Made a subscriber out of me

[@silkeschipper2670]

I’m ver young I’m a pre teen and some ppl say I can’t become an astronaut and I want to be one any advice or tips I wanna work at ESA bc I have a nationality! Please I need motivation

[@SpaceMog]

Sorry for the delay, but I think you can work at ESA if you want too. Its hard, and you will have to study hard and get yourself a PhD in physics or engineering to make sure you get a good chance. But you can do it! Good luck!

[@ayushfl567]

I have a question if this is the reason that moon is rusting so why it is rusting now why we are seeing the rusting is this rusting took place from many yrs or it is happening now Even though magnetotail oxygen is travelling from earth like for many yrs🤔🤔

[@SpaceMog]

Great question! Rust is a slow process, especially with the trace amounts of oxygen and water up there, so its probably been happening over many years and only now been seen

[@ayushfl567]

@@SpaceMog ya absolutely possiblities are there

[@titaniumdiveknife]

Your favourite sci-fi tv shows and episodes, please?

[@SpaceMog]

definitely a future video topic!

[@titaniumdiveknife]

@@SpaceMog YAAAAAY ;D

[@seraphin8999]

Thx now i finaly know❤

[@alnilam2151]

Oh ouch that hurt a little, you mean there's a difference prof??? In true & apparent, brightness that is! Does this, then, thus; also include a stipe for, the Real & Actual being False 2: My oh my how dim was I? \o/ As always: DrLieu {provider} of rational thought provoking study and research another excellent episode, maith agat! {\} \thats Gaeilge4 thanx/

[@ggman69]

Distance = Speed X Time

[@TheOrwell57]

If i were the big boss of Switzerland i would redirekt the annual budget for Swiss TV to you, 1.2 Bilion Sfr. ca.. And a letter to the South Park team is on the way. Dankeschön and all a nice time.

[@SpaceMog]

Aww you're very sweet :-)

[@olivierkatombe3374]

I thought it 's Time X Speed = distance

[@rbnzdave]

Speed or velocity, and yes, it is.

[@tonyp6631]

I honestly only knew of the moon laser and the light red shifting for determining methods before now. Very cool, Pythagoras would be proud if he came back. Then he'd go on to start another freaky sex cult. 'Pythagoreanism' "all thing in common amoung friends." "Come! share your ideas, share your possessions, share your wives. For I was sent by the gods to show you a new way of life. The planets move because of musical notes like mimes in the form of god on high. Come join me, Pythagoras in beautiful sunny Tijuana Mexico and " .. I Wikipedia'd Pythagoras sorry about the tangent.

[@SpaceMog]

😂

[@mballer]

I never knew.

[@HelloThere.....]

But isn’t it circular to use the spectrometry of known chemicals to determine redshifted light if you also use the light measured to determine the spectrometry of the star and it's chemical makeup? You're using your claim to prove your claim

[@alnilam2151]

This too, so cool!

[@milobem4458]

@1:25 that equation...

[@harritoivio2151]

How we know how far away big bangs are?

[@SpaceMog]

13.7 billion years - measured by extrapolation - great question! :-)

[@ZeroSpawn]

Also we only know of one big bang. If we discover more than this will prove the multi vers theories.

[@rbnzdave]

"They didnt took along a measuring tape" ? come on. kzbin.info/www/bejne/rIaXi594fNt4Zrs

[@SpaceMog]

Can you believe it ?

[@ABCXYZ-hw1nk]

Puter❤

[@SomeMind]

I understand the desire to simplify but I had to stop watching after "mirrors", retroreflectors and mirrors are very different.

[@andresavilan2387]

This is all garbage… Amazing…and many will believe…

[@SpaceMog]

Why would you think that ?

[@peteroreilly8060]

You are wrong

[@bettyg7710]

So basically what I hear in this lecture is they don’t know beyond our galaxy. You see parallax does not even get us outside our galaxy. The rest is supposition at best. All we can really say is, it is beyond our knowledge and capabilities at this time. We have no idea what kind of effects these great distances have on light and the entire electromagnetic spectrum. We really have no real frame of reference. You go ahead and believe, not me. Their arguments are too weak for me.

[@SpaceMog]

Youre 100% correct 😮‍💨