A Brief History of High-Energy Astronomy: 1700 - 1799
In Reverse Chronological Order
||Studies of the frequency of sunspots indicate a 35-year
period of lower than average solar activity, now called the Dalton
Minimum. This period was, likely not coincidentally, one with
cooler than average global temperatures, implying that the solar
luminosity was also reduced during this interval.
|1784 & 1795
||The English philosopher John Michell (in 1784) and the French
mathematician Pierre Laplace (in 1795) consider the problem of classical
bodies for which the force of gravity might be so strong that light cannot
escape from them, i.e., the escape velocity from their surfaces would be in
excess of the speed of light. These are the first `scientific' discussions
of what are today called black holes (and which really require the
framework of general relativity to describe their properties).
|13 Mar 1781
||Musician and (then) amateur astronomer William Herschel and his sister
`discover' the planet Uranus, the first `new' planet to be
since antiquity. In fact, it was later realized that Uranus had been observed
much earlier (in 1690
by John Flamsteed) but misidentified as a star and dubbed 34 Tauri.
|25 Dec 1758
||German amateur astronomer (and farmer) Johann Georg Palitzsch
is the first to observe the return of the
comet of 1682.. The comet is dubbed Halley's Comet
(P/Halley) in honor of
Edmond Halley, who had predicted its return (the comet actually
was about a year late!).
Thomas Wright, an English scientist (also an architect and
landscape gardener), publishes "An Original
Theory or New Hypothesis of the Universe" in which he argues (correctly)
that the band of the Milky Way which is visible in the sky is due to a
multitude of stars confined to a disk-like geometry. This
realization of the structure of our Galaxy was later taken up by others,
including Immanuel Kant and William Herschel.
Edmond Halley publishes the first measurements of the proper
motions of the `fixed' stars, e.g., the nearby stars Arcturus and Sirius,
by comparing their contemporary positions with those determined by Ptolemy and
Hipparchus during their lifetimes (87-150 CE and 190-120 BCE, respectively)
and realizing that they were different (Halley 1718, Phil. Trans., 30, 736).
Edmond Halley notes that the comets observed in 1531, 1607, &
1682 all appear to have similar orbital elements based on Newtonian
mechanics. He suggests that they are all the same object and predicts
that the comet will return in 1757.
We would like to thank the following individuals for their
contributions to this page:
Jesse S. Allen, and
Ian M. George
JPL's Space Calendar and the
Working Group for the History of Astronomy's
Astronomiae Historia (History of Astronomy) information pages.
Web page author: Stephen A. Drake (based on an original by Jesse S. Allen)
Web page maintainer: Stephen A. Drake
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Last modified: Wednesday, 22-Sep-2010 13:50:33 EDT