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Rubidium is the first alkali metal in the group to have a density higher than water. On Earth, natural rubidium comprises two isotopes: 72% is a stable isotope 85 Rb, and 28% is slightly radioactive 87 Rb, with a half-life of 48.8 billion years – more than three times as long as the estimated age of the universe.
5th century BC: The earliest documented mention of a spherical Earth comes from the Greeks in the 5th century BC. [31] It is known that the Indians modeled the Earth as spherical by 300 BC [32] 460 BC: Empedocles describes thermal expansion. [33] Late 5th century BC: Antiphon discovers the method of exhaustion, foreshadowing the concept of a limit.
Date Event leading to space exploration Country Researcher(s) Ref(s). 1610 First telescopic observation of the night sky: discovery of the Galilean moons, lunar craters and the phases of Venus. Venice: Galileo Galilei: 1668 First reflecting telescope. England: Isaac Newton: 1781 First telescopic discovery of planet . Great Britain: William ...
This is a timeline of Solar System exploration ordering events in the exploration of the Solar System by date of spacecraft launch. It includes: It includes: All spacecraft that have left Earth orbit for the purposes of Solar System exploration (or were launched with that intention but failed), including lunar probes .
Robert Hutchings Goddard (October 5, 1882 – August 10, 1945) [1] was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket, which was successfully launched on March 16, 1926. [2]
The oldest artifacts date from around 2000 BC. [19] Recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy in 1787. [1] 51 Antimony: 3000 BC 3000 BC Sumerians Middle East An artifact, said to be part of a vase, made of very pure antimony dating to about 3000 BC was found at Telloh, Chaldea (part of present-day Iraq ...
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
The rubidium–strontium dating method (Rb–Sr) is a radiometric dating technique, used by scientists to determine the age of rocks and minerals from their content of specific isotopes of rubidium (87 Rb) and strontium (87 Sr, 86 Sr). One of the two naturally occurring isotopes of rubidium, 87 Rb, decays to 87 Sr with a half-life of 49.