Chances are, if you need to know what time it is, you look at your phone.An astrolabe, an ancient instrument that maps the night sky to determine facts like the hour of the day or when the sun will rise, was once used by people.If you have an astrolabe, you can use it to figure out the time, as well as find out where different stars and constellations will be on a particular date.Happy looking at the stars!
Step 1: To get the zodiac date, move the alidade onto the calendar date.
You can use the current date or the future date.Find the zodiac date that it points to by aligning the alidade with the date.The dates are written around the circle on the back of the astrolabe.
Step 2: The rule should be aligned with the zodiac date.
This will show you the position of the sun and the stars.If the rule is placed on top of the date, you will have an accurate reading.The sun's path is shown in the ecliptic by zodiac signs.The sun is moving around the ecliptic counter-clockwise.
Step 3: The rule and rete should line up with the time of night.
When you want to view the stars, find the time along the outer edge of the astrolabe.The intersection point of the rule and rete needs to be rearranged so that it points towards that time.If you want to know what will be in the sky at 10:30 pm, align the rule and rete halfway between X and XI.
Step 4: To find their location, look at the stars above the horizon line.
You can see anything above the horizon line on the date and time that you choose.The rings tell you how high the stars will be.The star is directly overhead if it is at the center of the rings.The lower in the sky the stars are, the farther out from the zenith.The compass markings on the plate tell you which direction to look in.The star or constellation will be found in the east-southeast section of the sky.You will not be able to see the stars below the horizon line.
Step 5: The alidade should be aligned with the North Star.
The alidade will point towards the North Star if the astrolabe hangs down and turns it.The bar on the back of the astrolabe is called the alidade.If you don't have a ring, you can identify the top by looking for the "XII".If you want to see the North Star through the other end of the straw, line it up by looking through one end and rotating it.
Step 6: The measurement on the rim is where the alidade is pointing.
You can find the number on the outer rim of the astrolabe after aligning the alidade.The zenith angle is the angle between the star and an imaginary line that goes up from the earth.Make sure the alidade is lined up correctly.The left or right can throw off your reading.It might be easier to have a friend look at the measurement while you hold the alidade in place.
Step 7: The latitude is obtained by subtracting the zenith angle from 90.
The elevation angle is the angle between the North Star and the horizon.This is the same as the latitude where you are standing.The zenith angle is equal to 0 if you are standing at the North Pole.The latitude of the North Pole is 90 if youSubtract that from 90.
Step 8: The astrolabe should be hung by the ring at the top.
Any other way will distort your readings.TheXII is on the outer rim of the astrolabe.Pinch the top to hold it up if there is no ring on it.
Step 9: To find the altitude, adjust the alidade to point at the sun.
There is a rotating bar on the back of the astrolabe.Turn it so that it is facing towards the sun.The angle measurement that the alidade is sitting on is along the rim of the astrolabe.The number is the sun's altitude.It means the sun's altitude is 40 degrees if the angle reads 40.Don't look directly into the sun.When you are looking at the sun, wear sunglasses to protect your eyes.A friend can hold the astrolabe while you read.
Step 10: Line up the alidade with the calendar date to determine the zodiac date.
The zodiac and civil calendar dates can be found on the back of the astrolabe.To find the corresponding zodiac one, place the alidade over the current date.A zodiac date is similar to a calendar date but uses a sign instead of a month.The zodiac date of March 13 is Pisces 10.
Step 11: The front of the astrolabe has the correct zodiac date on it.
The top plate on the front of the astrolabe is where the zodiac dates are located.Put the rule on top of the zodiac date you just found after turning the instrument over.The ecliptic circle is a ring around the rete where the zodiac dates are.
Step 12: Line the rule and rete up with the sun's altitude.
The tympan is the base plate of the astrolabe.Line up the intersection point with the altitude you measured.The altitudes are written in degrees on the tympan.
Step 13: Find the time when the opposite end of the rule is pointing.
Look at the opposite end of the rule once you have it aligned.It will be resting on the outer rim of the astrolabe.The numbers around the outside edge of the astrolabe are similar to a clock.They are written in Roman numerals.If the end of the rule is halfway between the two, the time is 7:30.