Ernest Leonard Johnson (1891–1977) was a South Africanastronomer and a former staff member of theUnion Observatory in Johannesburg, South Africa. He is known for the discovery of 18asteroids between 1946–1951, as well as severalcomets.^[1] On 25 August 1949, he discovered48P/Johnson, aperiodic comet expected to pass no closer than 1.2 to 1.3 AU from our planet in 2025.^[2] Johnson received the "Donohoe Comet Medal" twice^[3]: 40 before retiring in 1956. He died in 1977.^[4]

Johnson was the son of William Johnson, a medical practitioner, and Rachel Sarah Joan Sanderson.^[4] He matriculated atGrey College, Bloemfontein, South Africa and started working on a mine but when his brother, Cecil Robert Johnson, was killed in a mining accident he applied for a position at theUnion Observatory inJohannesburg, South Africa. He started work there as a learner astronomer in 1914.^[5]

He served in the armed forces of theUnion of South Africa inWorld War I (1914-1918) during the campaign inGerman West Africa (nowNamibia) but was sent home owing to illness. He recovered and went toEngland where he served as abomber pilot for theRoyal Flying Corps. After the war he returned to the Union Observatory and remained there for the rest of his career.^[5]

Johnson produced star maps of the sky south of 19 degrees southdeclination, in collaboration withHarry Edwin Wood. In January 1935 he discovered a faint comet, that was visible for less than two months, while searching the sky in declination 52 degrees south. This comet was namedJohnson's comet 1935. He discovered a second comet in 1948.^[5]

Between August 1946 and July 1951, Johnson also discovered 18asteroids, the most important of which was named1580 Betulia. This asteroid was discovered on 22 May 1950 during itsclose approach to the earth. From 1921 to 1953, his observations of the asteroids and more than 30 comets were published in theCircular of the Union Observatory, Johannesburg.^[5]

Johnson was a member of theAstronomical Society of Southern Africa and contributed to the society'sMonthly Notes.^[5]

Discoveries of comets include:

• C/1935 A1 on 8 January 1935 (Cometa 1935)^[6]
• C/1948 R1 on 1 September 1948 (Comet 1948j)^[7]
• 48P/Johnson on 25 August 1949^[2]
• C/1949 K1 on 20 May 1949 (Comet 1949a and/or 1949d)^[3]

Johnson is credited by theMinor Planet Center with the discovery of 18 asteroids:.^[1]

In 1922 Johnson married Aisleen Devenish, with whom he had a daughter and a son. He retired from the observatory in December 1951 but continued to work until 1956, during which time he tested potential astronomical sites with portable reflecting telescopes for theEuropean Southern Observatory Organisation.

• List of minor planet discoverers § E. L. Johnson

• Vermeulen, D.J. (2006)Living amongst the stars at the Johannesburg Observatory. Johannesburg: Chris van Rensburg Publications

• Biographical Index to MNASSA and JASSA Prepared by I S Glass in 2003 (archived on 4 February 2012)
• A history of comet discovery from South Africa, T P Cooper, August 2003

• 1891 births
• 1977 deaths
• Discoverers of asteroids
• Discoveries by Ernest Leonard Johnson
• South African astronomers
• South African scientists

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