- a sundial tells time by means of

the sun. To be more specific it can only be used when there is sunlight or in the morning. It can't be used in the evening. You can't use it during a thunder storm in the morning, you can't also use it when the sun is covered by thick clouds or during a cloudy day. The image below is an example of an early sundial.

- these were very common

in the ancient world. These were located at some sacred prominent spots, perhaps over the hilltop, through a cleft in the hills on the far horizon, along a row of stones, or from an inner sanctuary. It determines solstices and equinoxes. Solstice is easier to observe and it is accurately measured by sight-lines. The image below is a natural example of sight-lines.

- a Stonehenge

is used as a celestial calendar, burial place, sacrificial altar and a defensive building during the early times. The image below is an example of a Stonehenge.

- "A quadrant is an

instrument that is used to measure angles up to 90°. It was originally proposed by Ptolemy as a better kind of astrolabe. Several different variations of the instrument were later produced by medieval Muslim astronomers."

- a telescope is used

to see distant objects. High class telescopes are made to see stars, planets, moons and other celestial bodies. The most powerful and advanced telescope of our present time is the Hubble Space Telescope made by NASA. There are two kinds of telescope, the reflecting telescope and the refracting telescope. The image below is an example of an early telescope.

- It was a simulator of the

ostensible motion of the planets. It was devised by Eudoxos of Knidos who tried to simulate the irregular motion of the planets with the combination of circular movements which were considered the only acceptable orbits for the eternal motion.It consisted of two concentric spheres (or rings). The internal sphere rested at inclination in the exterior sphere and bore the planet on its equator.

- It was the geocentric

astronomical model of Ptolemy which depicted and forecasted the orbits of the Sun, Moon and known planets on the ecliptic level. In the astronomical system of Ptolemy the Moon, Mercury, Venus, the Sun, Mars, Jupiter and Saturn revolved around the Earth, while the remainder stars were standing on an outer sphere.

) - It was an exceptional

astronomical instrument which depicted the celestial sphere and was used for the measurement of geographic length (longitude) and width (latitude) of the observed stars from any part of the Earth but

also reversely as locator of place (GPS) and also for the measurement of the Sun – Moon distance.

-

It was a measuring instrument which was used (in astronomy and navigation) for the calculation of astronomical sizes and (in topography and in construction) for the measurement of terrestrial distances (e.g. the height of a building).

It was an early

astronomical instrument suitable for measuring very small angles. It was used to calculate the visible angle and the distance

of celestial bodies from the Earth but also the distance between

them.

Hans Lippershey (1570 – September 1619), also known asJohann Lippershey or Lipperhey, was a German dutch spectacle-maker. Heis commonly associated with the invention of the telescope, although it is unclear if he was the first to build one. • Lippershey applied to the States General of the Netherlands on October 2, 1608, for a patent for his instrument "for seeing things far away as if they were nearby", beating another Dutch instrument-maker's patent, Jacob Metius, by a few weeks. Lippershey failed to receive a patent since the same claim for invention had also been made by other spectacle-makers but he was handsomely rewarded by the Dutch government for copies of his design.

The 1600s 1608:Hans Lippershey, a German-Dutch

lensmaker once said that he wanted to make an instrument “for seeing things far away as they were nearby.” He was the first person to ever think of the telescope.

1609:On hearing about this new

instrument, Italian physicist Galileo Galileibuilds his own. He improved Lippershey’sdesign and using his new telescope the following year, he discovers the four largest moons of Jupiter (Io, Ganymede, Callistoand Europa), sunspots on the surface of the Sun, the phases of Venus and physical features on the Moon - such as craters!

1659. 1666: After studying the reflection of light through prisms, Sir Isaac

Newton decides that the problem of chromatic aberration cannot be solved. He makes an improved version of the reflecting telescope. 1673:

Laurent Cassegrain, a catholic priest from France, develops a telescope that bears his name - the Cassegrain telescope. This instrument uses mirrors that are called hyperbolic and parabolic mirrors.

The 1700s 1721:English mathematician (and inventor of

the octant) John Hadley present a much-improved Newtonian telescope design.

1729:A huge development in refracting

telescope happens during this time when lawyer Chester Moore Hall makes a lens to reduce chromatic aberration even further. He made the lens by cementing two types of glass (crown and flint) together. He proved that Newton’s statement that

chromatic aberration could not be solved was incorrect!

1897:American astronomer Alvan Clark builds the

world’s largest (at that time!) existing refracting telescope - the Yerkes Telescope in Wisconsin. Because this telescope holds the largest glass lens possible before a telescope will begin to buckle under its own weight, astronomers decided that large telescopes should have mirrors instead of lenses.

he 2000s 2009: The Herschel Space Observatory is

launched. Bearing the name of astronomer, William Herschel, this space observatory is able to look into the really cold regions of space with its far infrared vision!

2010:The Gran Telescopio Canarias is built on

the island La Palma in the Canary Islands of Spain on the top of a volcanic peak 7,438 feet above sea level. It

is the largest telescope of our time.