Early astronomers used tools like the sundial, merkhet, quadrant, astrolabe, and cross-staff to measure the passage of time and the positions of stars and other astronomical objects. The telescope, invented in the late 16th century, revolutionized astronomy by allowing astronomers to observe celestial objects in greater detail. Units like the astronomical unit (AU) and light-year provide standardized measures for distances within our solar system and across the wider universe.

1. Tools Used by Early Astronomers

2. Sundial
Sundial: The sundial has been used
for more than 7000 ​years to
measure the passage of time.
The merkhet uses a string with a weight
on the end to ​accurately measure a
straight vertical line, much like a plumb
bob. A pair of merkhets were used to
establish a ​north-south line by lining them
up with the pole star. ​This allowed for the
measurement of night-time hours as it
measured when certain stars crossed a
marked ​meridian on the sundial.

3. Quadrant
Quadrant: was designed to measure a ​stars height above the
horizon.

4. Astrolabe
Astrolabe: The astrolabe was used
to make accurate ​charts of star
positions.

5. Cross-staff
Cross-staff: was used to measure the angle ​between the moon
and any given star.

6. EarlyTelescope
Early Telescope: The telescope was invented ​in the late 16th
century, it revolutionized astronomy.

7. AstronomicalUnits
Astronomical Units (AU): is used to measure ​distances inside our solar
system.
1 AU = the average distance from the center of the ​Earth to the center
of the Sun (149 599 000 km)

8. Light-year
Light-year: is the distance that light ​travels in
one year
Light travels at 300 000 km/s So 1light-year =
9.5 trillion km
Interesting fact: The light from stars can
take ​many thousands of years to reach us, so
some of ​the stars that we see at night may no
longer exist.

9. Light-year