How Far Away Is It - Chapter 5 - Nearby Stars (4K)

In this segment of our video book, we take a look at our stellar neighborhood and how we know how far away these nearby stars are.

We cover the first stellar parallax measurement form the star Cygni 61. This includes the definition of ‘parsec’ and ‘light year’. We then cover the Alpha Centauri system (Proxima Centauri, Alpha Centauri A & B), and use it to show how we calculate the mass of binary star systems. Then we examine our stellar neighborhood including: Barnard’s Star with its Proper Motion, Wolf 359, Lalande 21185, Sirius A & B, 61 Cygni, Altair, Fomalhaut with its planet, and Vega.

A deeper look into what we mean by ‘luminosity’ is outlined. We point out that it is measured in watts just like a light bulb and that its value over distance from a point source follows the ‘inverse square law’. We use our Sun as an example and introduce Einstein’s famous “energy = mass time the speed of light squared” formula.

We then cover some more stars including: Pollux, Arcturus, Capella, and Castor. Having reached the limits of ground based telescopes to measure parallax, we discuss the European Space Agency’s (ESA) Hipparcos satellite and the more distant stars it helped fined parallax for including: HD 189733, Aldebaran, Mizar, Spica, Mira, Polaris, and Antares. Along the way, we build the mass vs. luminosity empirical graph.

We then cover the new ESA satellite Gaia that is mapping over a billion stars in the Milky Way and nearby galaxies. We follow that with a look at a few stars too far for Hipparcos but well within the range of Gaia: Betelgeuse, CH Cyg, and Rigel.

We end by pointing out that parallax only takes us to a small percentage of stars in the Milky Way and that we’ll need to know more about light to go any further.

Music

@0:31: Tchaikovsky - Symphony No 6, Pathétique IV Finale. Prague Festival Orchestra; from “Must-Have Adagio Masterpieces”

@10:40: Suppe - Poet and Peasant Overture: Hungarian State Opera Orchestra & Janos Sandor, Janos Sandor, Hungarian State Opera Orchestra; from the album Franz von Suppé: Poet & Peasant

@17:51: Puccini - Manon Lescaut - Donna non vidi mai - I have never seen a woman like this; Sofia Philharmonic Orchestra; from album “100 Must-Have Opera Karaoke”

@20:38: Schubert - The Trout from album “A Calendar of Classics - A 12 CD Set Of Romantic Classics For Every Month Of The Year”

[rajmehta]

I go to sleep listening to your videos. I learn a few things new things about our Universe and your voice puts me to sleep

[bxnwvey]

In huge contrast to Alex Filipinko, Neil Degrasse-Tyson, et al, David Butler does not insult my intelligence. These are some of the most interesting, unpatronizing astronomy videos I've seen. The narration is excellent, and I enjoy watching them very much.

[triplikeido]

Excellent background classic music is perfect for the subject matter, as well as Mr. Butler's manner and style of teaching.

[adawg]

It’s incredible to just know how much you can learn on YouTube with a pair of eyes some ears and a brain you sir have taught me a lot

[milesstankovic]

Professionally presented with such clarity of topic.
IF only our College teachers could present topics to thus standard, we would have a greater number of high quality graduates.
Thank you
Miles

[klejs]

We are blessed to get this knowledge with you being such a calm and collected teacher. Thank you!

[geraldrice]

The Basil history lesson is excellent. The link between parallax and stars creating their own light is a fantastic connection.

[assortedtea]

I watch and listen to David Butler s videos to fall asleep at night 🙂

[diouranke]

pretty amazing when you consider how long stars live and how fleeting our lives are

[TheDrumstickEmpire]

4:57 that’s a rounded up version for those of you wondering light travels at 299, 792, 458 metres/second! for comparison sound travels at 343 meters per second!

[aliakdere]

I was roaming around youtube in many physics channel that I can find. Until I find your channel. So your channel became my only physics channel to watch and study by then. Informative, genuine, full of real physics not bullshit like some others do. Thank you Mr Butler.

[joqqy]

Great videos. I like the raw information presented, narrated calmly, without bombastic music, fast talking, bells and whistles. Reminds me of the superb old informative documentaries. This is how it should be done, thank you David.

[KeithShuler]

You've given me a lot to think about, and plenty to learn.

[kikeolvera]

Thanks David to share this! its a Jewel for all of us Who LOVE stars since childhood!!

[rauljrlara]

I rewatch these videos often when I'm bout to go to bed. So relaxing music and calm voice and very informative video .

[MsMsmak]

I really appreciate this work you do. I watch the videos multiple times because there is just so much to learn. Thank you thank you thank you!

[NelsonReyesJr]

What a fantastic documentary! You dont insult our intelligence by dumbing this down to elementary school level and you dont paralyze us with unconscionable vocabulary. EXCELLENT WORK!

[nicosmind]

There's only 2 things I find wrong with David Butler videos.




Not enough of them, and rarely long enough!


Was excited to see this new video :)

[seanl]

What an awesome guy. These videos are absolutely top notch. They teach so much I was never able to learn from any other person in such detail, it's truly amazing. I wish you a long, long and happy life, Mr Butler.. you definitely deserve it!

[finddings]

Best documentary film, voice is perfect for the video.