How astronomers define coordinates in the sky using Right Ascension and Declination. ~-~~-~~~-~~-~ Watch next: Solar Orbiter Discovers Surprising new Phenomenon in the Sun • Solar Orbiter Discover... ~-~~-~~~-~~-~
Can somebody please recommend a good astronomy calculations book or a resource for conversion between different Astronomical Coordinate System? @Launch Pad Astronomy
Not off the top of my head. Converting between RA/Dec to Alt/Az involves knowing your position on Earth and time. I’m sure there are resources out there you can google. Cheers!
I teach high school astronomy and we're all in quarantine from Covid-19 and I needed to get materials onto our online system fast. While looking for celestial sphere and celestial coordinate system videos I had to dig through youtube for a while before I found yours. They are the best I've come across. Thank you.
Please check the RU-vid channel of 'MICHEL VAN BIEZEN'. Go to play list of ASTRONOMY, then CHAPTER 2. 8th video of that chapter will explain it in such a way that you will get addicted to that channel like me. As you said you are a teacher, you will definitely get benefitted from his way and simplicity of teaching.
Clarifying the confusing "hours of Right Ascension" longitudinal coordinate system of the celestial sphere: Celestial "prime MERIDIAN" (or "zero HOUR") was chosen by choosing the meridian ("hour") which CROSSES the POINT on the sphere where the sun seems to cross the celestial equator in spring (March 21). (That POINT on the celestial sphere is called "the spring [vernal] equinox".) --------- Other meridians ("hours") are labeled by the following process: Outside the celestial sphere, (with the north celestial pole at the top), move ("ASCEND") to the RIGHT while drawing a meridian ("hour") every 1/24 around the sphere. Thus, there are 24 meridians (24 "hours" of R.A. "RIGHT ASCENSION"). Each hour is divided into 60 "minutes". Each "minute" is divided into 60 "seconds". I wrote the above, after learning from this video. Thank you for your video.
I absolutely LOVE this video, it's the first one that really got me to understand this. But as a follow-on, how does "Hour Angle" relate to the Equatorial Coordinate System?
I'm really glad you enjoyed the video. The Hour Angle can be used to describe the east-west or "RA" distance between two points in the sky. Usually it's measured off the meridian as positive if it's westward and negative if it's eastward. Cheers!
Clarifying the confusing "hours of Right Ascension" longitudinal coordinate system of the celestial sphere: Celestial "prime MERIDIAN" (or "zero HOUR") was chosen by choosing the meridian ("hour") which CROSSES the POINT on the sphere where the sun seems to cross the celestial equator in spring (March 21). (That POINT on the celestial sphere is called "the spring [vernal] equinox".) --------- Other meridians ("hours") are labeled by the following process: Outside the celestial sphere, (with the north celestial pole at the top), move ("ASCEND") to the RIGHT while drawing a meridian ("hour") every 1/24 around the sphere. Thus, there are 24 meridians (24 "hours" of R.A. "RIGHT ASCENSION"). Each hour is divided into 60 "minutes". Each "minute" is divided into 60 "seconds". I wrote the above, after learning from this video. Thank you for your video.
I have a question -- the earth is rotating and also revolving around sun; so isn't the coordinates of any celestial object on the celestial sphere (RA,DEC) going to change?
Sir would you suggest me the software to find for a given RA and DEC coordinate value in the laptop that whether it is associated with any astrophysical source or not? I am doing my thesis sir but I couldn't it.
But the Earth is moving beyond just its rotation - it is orbiting the sun, and the solar system is also moving. How does that _not_ change the coordinates of stars in this celestial sphere if Earth must be at the center of it? Or is the diameter of this sphere far more order of magnitudes larger than any of the quantities that describe the motion of our Earth and solar system?
The coordinate of the stars (RA/dec) change, only that very slowly... for our perception. You are thinking in terms of a Human scale of time and distances. But if you think in terms of astronomical distances, they are so colossally huge that thousands, even millions of years are needed for a visible change. Also, think that the stars we see are all relatively close to us and move around the center of the galaxy in a similar pattern than our Solar System.
Correct me I'm wrong, but I believe that you can't just point your telescope at some coordinate in the sky because it is constantly moving. So you either need to have your telescope mounted on a rotating base that compensates for the earth's rotation or you need to figure out what the coordinate of some location is in advance and use a fancy app that tells you the exact time when your telescope will be pointing at the location you're interested in.
Declination will always be the same, but right ascension will need calibrated each night on a known celestial object. And yeah you need a motor to keep track of the object over time, and the right ascension value drifts away and has to be treated as relative when switching targets
Could you elaborate on "The annual path of the sun."? It seems to me you're saying the ecliptic would be a line created by connecting the dots if we plotted the position the sun appears to be at the same time each day (say high noon) to an observer on Earth, relative to the background stars. Meaning the sun would appear to be directly overhead to an observer on Earths equator at noon on the vernal equinox, but in midsummer, it would appear directly overhead to someone at 23 degrees north latitude?
Yes, that's what I'm getting at. Of course, by "path" I mean the apparent path of the Sun around the sky, which is ultimately a manifestation of our annual path around the Sun. And you're correct that the Sun will be at the zenith as viewed from the equator at local noon when the Sun is on both equinoxes. I have a video on that where I discuss the seasons: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pJHF93oFRq8.html
Firstly thanks for these videos! Regarding right ascension - Does this look correct: Say I want to find Sirius around April 21st, rounding its RA to 6 hours and accounting for a month of earth motion 30deg / 2 hours = RA 4. Do I need to look where the sun sets then go east along the horizon around 60 degrees then from my zenith (I'm at 53 deg north) look south approximately 65 - 70deg (-53 - 16 declination)?
how do i use the bible to decipher the astromy thingy. ezelkill described the celestial sphere not aliens. when it says on the 10th month on the 10th day blah blah. is it read declination no of 10 degrees 10 hours 0 seconds 0 minutes???? also where on earth do i apply the coordinates in the bible. where should i be standing when i look up
