The Sky Part 1: Local Sky and Alt-Az / Horizon Coordinates 

Thank you very much!

@@LaunchPadAstronomy My main confusion as to how to draw this imaginary line from the moon to the nearest horizon point during its celestial transition when the moon is closest to its zenith if we are situated near the equator. In lower latitudes, this is not such an issue because the moon's altitude is relatively closer to the horizon and we know where North is. But when the moon is high up that imaginary arc to the horizon could end up anywhere on the horizon. Knowing the zenith's time of the moon and having a watch would take care of proper calculations. But how would Colombus know that crossing the Atlantic with no watch in the middle of the ocean?

You’re certainly welcome!

So obvious. Keep it to yourself.

@@marvel438 helpful actually

Thank you Issac!

Imagine you’re standing outside facing south. East is to your left and west is to your right. Now imagine you look up at the sky while still facing south. East is still to your left and west is still toward your right. Hope that helps!

Glad it was helpful!

Thank you!

Thanks! The first point of Aries / vernal equinox is by definition at RA: 0h; Dec: 0°. But as far as being able to point to it, it's really just a matter of familiarity with the sky and knowing where to look (hint: Pices :) )

@@LaunchPadAstronomy thank you. I mean, to practice searching it, without any programs or without 0 AR or 0 DEC of the EQ mount

Right, you wouldn't need a program. Just a good star map so you know what pattern of stars to look for. I'd pick a pattern that surrounds or "points" to the VE and practice looking for that.

Yep

Its correct, you have to imagine lying down to understand this diagram. Your toes point south as seen in the video, and your head points north. That means your left hand faces east (which is why east is on the left) and your right hand faces west (which is why west is pictured to be right).

Thank you! The thing about this system is that while it can describe every point on the sky, Earth rotates underneath it, so everything in the sky appears to make a circular path around the celestial sphere (even the north star, though it's hard to notice). So this system will only describe the location of a star or planet at any given moment. There's another system we use that's independent of Earth's rotation, which I discuss in another video. Cheers!

Glad you liked it

Go outside and face south. Hold your compass overhead. Which direction is East? :)

Yep.

Because we’re looking up :) To see what I mean, go outside and face south. North is behind you. Which way is east? Which way is west. Now look up at the sky and ask yourself which way is east and which way is west.

i hope this helps. Altitude azimuth coordinate system is a local system. That is it is observer oriented. if you're in the North pole and then you're friend is at the south pole. Both of your Zeniths are not the same. you take a point directly above you as zenith (somewhere in the north), and your friend take a point directly above him/her as zenith(obviously in the south). if zeniths differ (they definitely differ from places that are far from each other, like two countries or two continents) the altitude and azimuth also differs. So the sun for observer 1 in India is at its highest point only for him and people from his city or state and not for the observer 2 from china or japan.

quick question? when you say observer 1 in India and observer 2 in China or Japan... their all right next to eachother.... Where is Japan located in the World. This island nation of East Asia located in the Pacific Ocean is officially called the Nippon Koku, which means State of Japan. The neighboring countries of North Korea, South Korea, Russia and China are located west of Japan India is positioned on the Indian subcontinent in south-central Asia, and is located in both the eastern and northern hemispheres. India bordered by the Arabian Sea, Bay of Bengal, Gulf of Mannar, Indian Ocean, and the countries of Pakistan, China, Nepal, Bhutan, Bangladesh and Burma (Myanmar). why would the sun be any different for observer 2? from observer 1? and Another thing ANTARCTICA IS ON the South pole.. NO ONE OR NOTHING LIVES IN ANTARCTICA

en.m.wikipedia.org/wiki/Sea_level look up Vertical datum....heres the link en.m.wikipedia.org/wiki/Geodetic_datum#Vertical_datum A vertical datum is a reference surface for vertical positions, such as the elevations of Earth features including terrain, bathymetry, water level, and man-made structures. The same position on a spheroid has a different angle for latitude depending on whether the angle is measured from the normal line segment center of the ellipsoid or the line segment straight from the center Look up Geodetic coordinates Note that the "flatness" of the spheroid is greater than that of the hole Earth; as a result, the corresponding difference between the "geodetic" and "geocentric" In geodetic coordinates, the Earth's surface is approximated by an ellipsoid, and locations near the surface are described in terms of latitude , longitude and height. Geodetic versus geocentric latitude Geodetic latitude resp. altitude, is different from geocentric latitude, resp. altitude. Geodetic latitude is determined by the angle between the equatorial plane and normal to the ellipsoid, whereas geocentric latitude is determined by the angle between the equatorial plane and line joining the point to the centre of the ellipsoid Unless otherwise specified, latitude is geodetic latitude. The WGS 84 datum surface is an oblate spheroid with equatorial radius a = 6378137 m at the equator and flattening f = 1/298.257223563. The refined value of the WGS 84 gravitational constant (mass of Earth’s atmosphere included) is GM = 3986004.418×108 m³/s². The angular velocity of the Earth is defined to be ω = 72.92115×10−6 rad/s.

_''In one years time they make a 360° rotation around the pole star, "Polaris''_ Really one year? Try one day! _""Polaris did NOT move off the line through out the entire night as every other star in the sky did''_ Wrong! Polaris rotated around the North Celestial Pole like the other stars. Polaris is not at the NCP. Look closely. _''Stars have been studied and recorded for centuries. ''_ Yep, that's how we know how it all works. You should study them more.