The Telescope
Because the inner planets are made of rock but the outer planets are made of gas(except for Pluto).
All the inner planets are rocky or terrestrial planets.
They are made of less dense materials. While the inner planets are made primarily of rock, the outer planets are made mostly of hydrogen and helium.
There are four planets that are made out of gas: Jupiter, Saturn, Urans and Neptune. These planets are called the "gas giants" . The other four planets (Earth, Mercury, Venus and Mars) are mostly made out of rock.
the inner planets are made of rock, ice and other materials while the outer planets are made of different kinds of gases except for pluto.
the telescope
It was made when the big bang happen i think?
people coming
The answer is The Microscope.
microscope
Voltmeters were made possible by an 1819 discovery by Hans Oersted. The first voltmeter were made soon after that.
I would say optics, IE the Microscope.
X-ray diffraction
by the discoveries of the monk George Mendel, I think...
The hieroglyphics of Egypt are one of the oldest forms of the written word known to man. The discovery of the Rosetta stone made it possible to read the hieroglyphs.
Jupiter has no planets but it has a lot of moons. The big ones, discovered by Galileo are Io, Europa, Ganymede and Callisto. Galileo wanted the credit for the discovery but did not want to reveal the discovery, so he announced it with a Latin anagram, so that when someone else made the discovery he could say, 'aha! I knew that first!'. That's the way they used to behave in those days (Galileo anyway).
What important discovery was made there