to be able to set both the day and the time on the

Last updated: 3/21/2023

to be able to set both the day and the time on the planisphere in order to figure out which part of the sky will be visible The scales on the planisphere let us do just that Operationally you need only line up the date which is written on the star disk with the time which is written on the horizon mask That will provide you with a map of the current sky As time passes you ll need to spin the star disk to keep the date lined up with the current time This spinning over the course of the night is due to the Earth s spin You ve set up the planisphere to represent a particular day of the year which corresponds to a particular point in the Earth s orbit around the Sun This means you ve accounted for both the diurnal daily motion and the annual yearly motion of the sky Questions 1 Find Polaris Hint you need to look towards the North Measure its altitude above the horizon with your astrolabe or by using the pinky rule Pinky 1 thumb 2 fist 10 Altitude of Polaris 2 Find the Winter Triangle it is made up of Sirius Procyon and Betelgeuse What is the angular distance between Sirius and Procyon Between Sirius and Betelgeuse Use the pinky rule Distance bet Sirius and Procyon Distance bet Sirius and Betelgeuse 3 If the Moon is above the horizon find it and measure its altitude Phase Altitude Time and Date 4 Using the chart on the next page draw the stars and constellations that you can see facing south and facing north Don t copy your star chart or planisphere Light pollution prevents us from seeing everything Just draw what YOU can see MAKE SURE TO LABEL WHAT YOU DRAW