hello this is a video tutorial on the program stellarium I'm running the Mac version and I'm going to show you a couple of things about how the Sun of the moon move in the sky I have set up the program for New Haven and it's 12 o'clock Eastern Standard Time on February the 6th so there's the Sun in the south not quite on them Radian look close and if I look over to the east there you see the moon not quite first quarter now I'm zoomed out a lot to the moon very small if i zoom in a bit more I can do that using the mouse wheel or the arrow keys and zoom in here the zoom and a fair bit in order to see that phase so what I can do is enlarge the size of the moon so it's a bit easier to see if I go to sky and viewing options under sky I can say scale moon and now I can see the moon four times bigger than actual size so that it's a little bit easier to see the phase so that phase makes sense because it's about 90 degrees to the east from the Sun so that's first quarter and it's illuminated on the side towards the Sun of course I want to turn on a couple of other sky markings so I'll go back to sky and viewing options markings I want to turn on the local Meridian so you can see where the Sun is relative to due south and north there's the local Meridian I'm you see the sun's a little bit behind the Meridian a little bit east of Meridian that's just the equation of time equation of time correction I also want to turn on the celestial equator and the ecliptic I think oh that's the ecliptic by definition the Sun is always on the ecliptic and then this blue line is the celestial equator you can see the Sun is quite a bit south of the celestial equator in February you can see that its declination is this number right here and so it's about negative 15 degrees 30 to 33 I guess arc minutes so quite a bit far south because we're still in the winter months and day after day of the Sun is when you creep along the ecliptic towards the celestial equator and cross it on the spring Equinox in March I can also turn off the atmosphere so if I go down to our do this toolbar there's an option for atmosphere turn on and off are going to sit the a key to toggle that and now I can see the stars and the stars are useful marker of the celestial sphere itself over the course of the day if I lit timeline forward but here we are see time advancing here the Sun and the stars and the moon and everything moves from east west as your rotates to the east so I'll also turn on the constellation lines the classical constellation lines and constellation labels so you can see where where the celestial sphere is now where is the Sun going to be tomorrow let's advance by one day so if I go to the date and time window and go to February 6 7th 8th 9th you can see the Sun is coming back to about the same place in the local sky but that's how we keep time is the end the hour angle of the Sun the angle between the Sun and the meridian so if we come back to 236 every day so it's going to be in about the same place but it's also moving up in the local sky you can see that it's moving up that's because its declination is getting less and less than angle is getting less and less and it's also creeping around relative to the star so if we started in Capricorn and now we've moved to Aquarius and a month later we would actually be also then in Pisces now right about here the Sun is crossing the celestial equator so that is the spring equinox by definition that's 0 hours right ascension and see we're not quite on the equinox at 2:30 on March 20th but we're very very close it says the right to sun's right ascension is 23 hours 59 minutes and 41 seconds so just have to creep around a little bit further to be at zero and negative zero degrees to our comminute so it's just a matter of a couple of hours before the Sun truely crosses the ecliptic crosses the equator I mean so that is by definition with bring equinox when that happens at that exact moment now if I were to step forward by a sidereal day instead of a solar day you would see the Stars essentially frozen because the Earth rotates 360 degrees in one sidereal day so I can do that by hitting option plus that steps forward by a sidereal day of star day so I'm stepping forward by a side aerial day here and you see that the month the day of data the month is increasing by one day but the time is going back by four minutes every step and that's because a sidereal day is four minutes shorter than a solar day now you can see the Sun creeping along the ecliptic keep going here there it is going from right to left across the sky which is to the east towards the eastern horizon so the Sun moves to the east along the ecliptic about one degree per day as it goes through all of the constellations of the zodiac I want to see the moon come by as well so I'm going to step forward a few more days until we see the moon there's the moon right there so there you see an old crescent moon there's a new moon right between those two points and as we keep going through the moon is also moving to the east close to the ecliptic but not exactly on the ecliptic so there it keeps going around to the east and there's another first quarter in May and so forth I'm going to go back to February so I'm going to set my clock here for February 6th and I'm going to see where the moon is there's the moon and I'm curious to know if there could be a lunar eclipse the moon orbits close to the ecliptic but not exactly on the ecliptic so no lunar eclipses right now because the phase is wrong the moon has to be full for a lunar eclipse because it has to be opposite the Sun in the sky so if we go forward a couple of days starts to head down in below the horizon at 1:00 in the afternoon so let's go to later the full moon rises opposite the sunset so we'll go closer to sunset here we are at 622 in the evening and let's keep stepping forward and we get a woman right about there that looks like a a full moon and are we going to have a lunar eclipse no I can see re easily that the moon is nowhere close to the ecliptic so I took quite a fart quite a bit south of the ecliptic so the Earth's shadow is somewhere around there the moon's over there no lunar eclipses this month well what about next month like a little later in the evening so the moon's a little higher in the sky well I need to step forward by one cycle of moon phases and I could just do that day by day but I know it's 29 and a half days ahead I'm going to jump ahead to March 16th should actually be 30 days and there we see a full moon again and it's a little closer to the ecliptic but still not on the ecliptic and it's also south of the equator now so we're getting close to the Sun being on the spring equinox let's go to April so we'll get at April 15th oh ho now the moon is very close to the ecliptic have to be careful though because I remember I enlarged the moon by a factor of four I'm going to zoom in a bit and I'm going to turn off that enlarging so I'll say sky don't make the moon too big nevertheless I can see that there's definitely the full moon is very close to the ecliptic so when is the Eclipse well this is April 15th in the evening 1024 so we need to find how do we make the moon move closer to the ecliptic so we can see that eclipses happen so let's see I'm going to just test by going forward and time a bit I keep the moon centered though so I'll click on the moon and hit the spacebar like it's moving away from the ecliptic so I go back in time and it looks like it's going to go below the ground it's going to hide the ground so I'll hide the ground by hitting the G key or hitting that icon another option that's useful is to keep the equator horizontal so when you don't care about the local horizon you're tracking something in the sky sometimes it's helpful to just keep the equator horizontal stabiliser and there is an option for that here if I click on equatorial mount mode then what it will do is always keep the horizon horizontal so let me go back to the moon so click on the moon and the space bar to keep centered and then as iam in a bit there we go so here we are now 7:25 on April 15th let's keep going back in time so see when the moon is eclipsed if it is so I'm going to go earlier in the day now this would actually be during the day time but you see the moon is getting closer to the ecliptic alright so here is aa ha so it's not when this earth when the moon's right on the ecliptic but there you can see the Earth's shadow falling on the moon now around 1:30 in the morning Eastern Standard Time and we head into you a total eclipse with partial eclipses there's total eclipse right about there that's about 207 in the morning and the Eclipse is going to last for about an hour and then we'll have the moon come out right about there now I'm curious where this is in the sky so I'm going to go back to that or I'm going to go back to Horizon mode and I'm going to bring back the grounds it's at the G key and close this and I want to zoom out so there we can see where the moon is going to be when it's eclipse on the morning of February 15th