Fred Lawrence Whipple (1906–2004) was a pretty smart astronomer who was professor of Astronomy at Harvard University from 1950 until 1977.
After taking a class in astronomy, he enlisted at the University of California, Berkeley where he obtained his PhD in Astronomy in 1931. While in graduate school, he helped map the orbit of the newly discovered planet Pluto.
He joined Harvard College Observatory in 1931 and studied the trajectories of meteors, confirming that they originated within the solar system rather than from interstellar space.
In 1933, he discovered the periodic comet 36P/Whipple and the asteroid 1252 Celestia. He also discovered or co-discovered five other non-periodic comets, the first of which was C/1932 P1 Peltier-Whipple, independently discovered by the famed amateur astronomer Leslie Peltier.
During World War II, he invented a device for cutting tinfoil into chaff to confuse enemy radar tracking Allied aircraft. He was awarded a Certificate of Merit for this in 1948.
He also invented a “meteor bumper” or “Whipple shield”, which protects spacecraft from impact by small particles by vaporizing them.
He was also an astronomer who evidently believed in extraterrestrial water because in 1950 he invented the “dirty snowball” hypothesis of cometary composition:
During these years (in the early 1950s), he wrote a series of influential papers entitled A Comet Model, published in Astrophysical Journal
In these papers, he proposed the “icy conglomerate” hypothesis of comet composition (later called the “dirty snowball” hypothesis).
The total lack of evidence to support the “dirty snowball” theory has caused the theory to morph [in recent years] into the “icy dirtball” hypothesis.
The basic features of this hypothesis were later confirmed, however the exact amount (and thus the importance) of ices in a comet is an active field of research, with most of the recently obtained data pointing to a low contribution of ices to a comet’s mass (dubbed the “icy dirtball” hypothesis).
Unfortunately for astronomy Fred Whipple abandoned the Scientific Method and resorted to the “visualized” technique [i.e. imaginative invention].
The SAO/NASA Astrophysics Data System
The initial failure of Fred Whipple visualisation stems from his assumption that cometary composition differs from the composition of meteorites. This is baffling because comets are associated with meteor showers [like the Taurids and the Leonids] and comets are also known to break up into fragments [i.e. meteorites].
The Taurids are an annual meteor shower associated with the comet Encke. They are named after their radiant point in the constellation Taurus, where they are seen to come from in the sky. Because of their occurrence in late October and early November, they are also called Halloween fireballs.
Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years, breaking into several pieces and releasing material by normal cometary activity or perhaps occasionally by close encounters with the gravitational field of Earth or other planets (Whipple, 1940; Klačka, 1999). In total, this stream of matter is the largest in the inner solar system. Due to the stream’s size, the Earth takes several weeks to pass through it, causing an extended period of meteor activity, compared with the much smaller periods of activity in other showers. The Taurids are also made up of weightier material, pebbles instead of dust grains.
Image Credit: NASA
The upper frame of this Hubble Space Telescope image captures the explosive disintegration of two separate fragments of Comet Schwassman-Wachmann 3 in April, 2006. The relationship of these two fragments to two other fragments from earlier break-up is evident in the lower Hubble image
The leonid vandeski is a prolific meteor shower associated with the comet Tempel-Tuttle.
The Leonids get their name from the location of their radiant in the constellation Leo: the meteors appear to radiate from that point in the sky. Their proper Greek name should be Leontids, but the word was initially constructed as a Greek/Latin hybrid and it is being used since.
They tend to peak in November.
Earth moves through the meteoroid stream of particles left from the passages of a comet. The stream comprises solid particles, known as meteoroids, ejected by the comet as its frozen gases evaporate under the heat of the Sun when it is close enough – typically closer than Jupiter’s orbit.
The Leonids are a fast moving stream which come close to or cross the path of the Earth and impact the Earth at 72 km/s. Leonids in particular are well known for having bright meteors or fireballs which may be 9 mm across and have 85 g of mass and punch into the atmosphere with the kinetic energy of a car hitting at 60 mph. An annual Leonid shower may deposit 12 or 13 tons of particles across the entire planet. Sometimes these trails of meteoroids cause meteor showers.
Unfortunately, Fred Whipple chose to ignore his “chemical knowledge of the meteoric material comes from the spectra of meteors, which tell us that Fe, Ca, Mn, Mg, Cr, Si, Ni, Al and Na, at least, are present”.
The second failure of Fred Whipple’s visualisation technique was that he explicitly imagined molecules that had not been observed:
“The model predicts a large excess of unobserved hydrides, H2O, NH3 and CH4 molecules, as compared to the observed CO+, C2 and CN.”
The third failure of Fred Whipple’s visualisation technique was his evasive and inventive explanation for cometary tails that point away from the sun. The inventive aspect was needed because the “vaporization of the ices by externally applied solar radiation” [or more simply: “melt and vaporize”] would generate a gaseous tail that simply followed the comet’s trajectory. Therefore, to generate a tail point away from the sun Whipple introduced the concept of a rotating cometary nucleus where the rotation has a “forward” sense so that a “component” of the “vaporized ices” is emitted towards “the antapex of motion”. The evasive aspect of the explanation is indicated by the use of the word “component” which means some [undefined] fraction of the melted and vaporised ices.
The fourth failure of Fred Whipple’s visualisation technique was his total failure to explain the spectacularly bright cometary comas [which do not look like “dirty snowballs” simply melting due to solar radiation].
The fifth failure of Fred Whipple’s visualisation technique was his total failure to explain the variations in brightness of comet Encke [which are associated with the solar cycle].
The sixth failure of Fred Whipple’s visualisation technique was his total failure to explain the observed “synchronic” formations in cometary tails which Vsekhsvyat-skii [from Kiev University] concluded were of an “electromagnetic” nature.
The Nature of “Synchronic” Formations in Comets’ Tails.
Vsekhsvyat-Skii, S. K. – Soviet Astronomy, Vol. 3, p.490
SAO/NASA Astrophysics Data System (ADS)
The seventh failure of Fred Whipple’s visualisation technique was his total failure to explain the periodic outbursts of comet Schwassmann-Wachmann [which has an orbit just beyond Jupiter]. The orbit of Jupiter ranges between 4.950 and 5.458 AU and the solar radiation received by Jupiter ranges between 55.8 and 45.9 watts per square metre [compared to Earth’s 1,413 – 1,321 watts per square metre].
Astrophysical Journal, vol. 122, p. 190-195 (1955).
SAO/NASA Astrophysics Data System (ADS)
Overall, Fred Whipple’s visualisation technique was a non-scientific work of imagination. He ignored observational evidence regarding comets and especially overlooked observations regarding Comet Encke [which was the subject of his first Comet Model paper in 1950]. Evidently, Fred Whipple’s faith in extraterrestrial water and “dirty snowballs” caused him to abandon the Scientific Method.