[The following is written in the top right corner of the document] Lowell Observatory, Flagstaff, Arizona, April 17, 1942
[The following is written in the top left of the document] Dr. R.S. Richardson, Mount Wilson Observatory, Pasadena, California.
Dear Dr. Richardson:
I read with considerable interest your article in the 1942 February issue of Publ. A.S.P., pages 19-23. Your assumption of a small, undiscovered planet slightly beyond the aphelion point of the orbit of Halley’s Comet to explain the perihelion passage delay of 2.7 days in 1910, is of particular interest. Since I have done considerable work in searching for possibly new planets within the zone of 10 to 200 A.U. distant from the Sun, I thought you would like to know something of the magnitude limit and degree of thoroughness of this search, in connection with your hypothetical planet. Since the search along and near the Ecliptic with the 13-inch Lawrence Lowell Telescope on one-hour exposure plates was conducted about a decade ago, it was necessary to compute back from the present position of the hypothetical planet which you five at:
α= 16h, δ=-20°. Adopting the four assumptions you have made (as stated on page 22) and considering the case of 35.3 A.U., or 0.1 A.U. Greater than the aphelion distance of Halley’s Comet, the period of the hypothetical planet turns out to be about 210 years. Thus, the annual motion across the sky amounts to 1.7 degrees. Therefore, in 1930, the planet was 20 degrees westward from its present position. An inclination and longitude of node similar to that of Haley’s Comet would place the planet 4 degrees north
Richardson, Robert S. (Robert Shirley), 1902-1981; Tombaugh, Clyde William, 1906-1997
Folder Description
Contains documents from Tombaugh's tenure on the Observatory staff, 1929-1945, as well as a small amount of material relating to later projects that Tombaugh worked on at Lowell Observatory in the 1950s.
Mount Wilson Observatory; Astronomical Society of the Pacific; Cowell, P. H. (Philip Herbert), 1870-1949; Crommelin, A. C. de la (Andrew Claude), 1865-1939; Halley's comet
Digital Publisher
New Mexico State University Library
Collection
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Source
Scan produced from physical item held by the NMSU Library Archives & Special Collections Department
Mount Wilson Observatory; Astronomical Society of the Pacific; Halley's comet
Date Original
1942-04-17
Digital Publisher
New Mexico State University Library
Collection
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Digital Identifier
Ms0407pp068018_0030001.tif
Source
Scan produced from physical item held by the NMSU Library Archives & Special Collections Department
Type
Text
Format
image/tiff
Language
eng
OCR
[The following is written in the top right corner of the document] Lowell Observatory, Flagstaff, Arizona, April 17, 1942
[The following is written in the top left of the document] Dr. R.S. Richardson, Mount Wilson Observatory, Pasadena, California.
Dear Dr. Richardson:
I read with considerable interest your article in the 1942 February issue of Publ. A.S.P., pages 19-23. Your assumption of a small, undiscovered planet slightly beyond the aphelion point of the orbit of Halley’s Comet to explain the perihelion passage delay of 2.7 days in 1910, is of particular interest. Since I have done considerable work in searching for possibly new planets within the zone of 10 to 200 A.U. distant from the Sun, I thought you would like to know something of the magnitude limit and degree of thoroughness of this search, in connection with your hypothetical planet. Since the search along and near the Ecliptic with the 13-inch Lawrence Lowell Telescope on one-hour exposure plates was conducted about a decade ago, it was necessary to compute back from the present position of the hypothetical planet which you five at:
α= 16h, δ=-20°. Adopting the four assumptions you have made (as stated on page 22) and considering the case of 35.3 A.U., or 0.1 A.U. Greater than the aphelion distance of Halley’s Comet, the period of the hypothetical planet turns out to be about 210 years. Thus, the annual motion across the sky amounts to 1.7 degrees. Therefore, in 1930, the planet was 20 degrees westward from its present position. An inclination and longitude of node similar to that of Haley’s Comet would place the planet 4 degrees north
