Welcome to Learn the Sky, your online resource for learning about the stars and constellations.
Welcome, my name is Janine and in this video we're going to take a look at a system of
navigation called right ascension and declination. This is one of my videos in the versus series,
so be sure to check out other videos in which we compare two concepts in astronomy. So when
astronomers are studying the sky, how do they know which portions to look at and to get exact
coordinates in order to make sure they're on the same page with other astronomers? Well, this
system is called right ascension and declination. If we took latitude and longitude on Earth,
so longitude going down, latitude going across, and we projected those lines outward and on to the sky
and the celestial sphere that's how we have declination and right ascension. So declination
in astronomy is comparable to geographic latitude, and right ascension is comparable
to longitude. Astronomers use this system in order to coordinate their research
efforts and simply it makes sure that everybody is on the same page when we're looking at the sky.
So often in my videos I show different star maps that are released by the International
Astronomical Union, and by the way these are considered to be the official star patterns that
were created in 1930, and here you can see that there are measurements here both going across
and going up and down ,and these are measurements of right ascension and declination. So right
ascension is much like longitude, how we talk about it on the Earth's globe, and declination is a lot
like latitude, and the way we measure them is slightly different. So in this animation what
we can see is how the celestial sphere is oriented. We have the Earth inside of the celestial sphere
showing you the equator and North and South Pole, but then we take those lines and we project them
onto the celestial sphere. We also take Earth's orbital plane, which is known as the ecliptic,
and here you can see these lines of latitude and longitude correlate with right ascension
and declination. So you can have a particular star point in the sky and measure its right ascension
and its declination on the celestial sphere Say we pick another star, like Sirius. Sirius has a very
specific right ascension as well as declination. So the way I would often use this as an astronomer
when I was using a telescope, I mostly use binoculars at this point, so again right ascension
are simply celestial coordinates that astronomers use. It measures east to west coordinates and it's
very similar to longitude, except it just has to deal with the celestial sphere.
We measure right ascension in hours, minutes, and seconds. I gave you an example of this down below.
This is the right ascension for this very bright star called Vega in the constellation of Lyra.
If you want to learn more about Lyra I do have a video all about it how to find it. Declination
these are also just another form of celestial coordinates that astronomers use, and it measures
the north to south coordinates, and it's synonymous with latitude. We measure declination in degrees,
arc minutes, and arc seconds. So here I gave you an example of what declination would look
like. Here is the degree, arc minutes, arc seconds, and this again gives you the declination for Vega,
and at the end of this video I'm going to give you another right ascension and declination to
go search and find and see what you come up with, kind of like a little scavenger hunt.
So let's review these concepts: right ascension and declination. How are they similar? Well,
they're both a form of celestial coordinates, but right ascension measures east to west,
it's similar to longitude, and we use hours, degrees, and minutes. Declination measures north
to south coordinates, it's similar to latitude, but we use hours, arc minutes, and arc seconds. So
when you look at these different measurements, on this channel I often use these types of maps that
were released by the International Astronomical Union, you can see that these measurements here
are on the side, so when you see degrees you should be thinking declination. So these lines that I'm
tracing out right here, that's declination, but if you see hours you should be thinking right
ascension, very similar to longitude. So the way I use this in my daily life is I really kind
of don't, I don't, I'm not using a telescope to observe the sky right now, but if I were I would
have the type of telescope I have is one of the ones where you can punch in your coordinates as
to where you want to go and then it very nicely lines up with what you're trying to see in the sky.
So that's how I would be using right ascension and declination, but if you are a telescope user right
ascension and declination is really something you would be using all the time, because it gives you
a direction as to where you should be looking in the sky to find particular objects. So to wrap up,
using right ascension and declination is very important when you are working with telescopes.
The time I was using it is when I was spending time on Mauna Kea doing volunteering up there
in Hawaii, and I would have the telescopes there at the visitor center, and I would punch in the
coordinates that I wanted to see, and then that's how I would find those different objects that I
wanted to see, and it was it was a lot of fun. It made stargazing a lot easier I think, as opposed
to just saying 'look to the right' or 'to the left,' it gives you very specific coordinates. So we've
come to the end of this video, and I wanted to give you a challenge to go find something on my channel.
So I want you to see if you can try to find this star. I gave you right ascension and declination.
So, go look up these coordinates and see what star this is and then go see if you can find a video
on my channel about this star, drop me a comment, and let me know if you were able
to find this video. It's about one of my favorite stars and one of my favorite creatures. I'll say no
more there, but I think it'd be fun to try to send you guys on a scavenger hunt, and drop a
comment if you were able to figure out what this star is. So, thank you so much for watching. I
really appreciate it. I hope this was helpful for you to determine the difference between
right ascension and declination, just kind of think of it as latitude and longitude, but projected onto
the night sky and giving it a different name. It's as simple as that. Thank you again for watching,
I hope to see you guys here again. Let me know what you think in the comments about my versus
video. It's a new series that I'm doing and I'm excited about it. So, thank you so much for watching.
Remember it takes time, patience, and practice to view the stars. So keep going outside, spend good
time in nature, and keep looking up. If you're new to this channel be sure to click the subscribe
button and hit the bell for notifications about all new videos. If you'd like to learn about the
sky in greater detail be sure to visit my website. I've got some freebies for you to
download as well as online lessons and classes for you to experience, so be sure to check them out.