1858day.year
Modified Julian Day zero.
On this day in 1858, the Modified Julian Day count commenced, providing a simplified continuous count of days for astronomical and scientific purposes.
Starting on November 17, 1858, the Modified Julian Day (MJD) system began at midnight, counting days sequentially from this epoch to streamline astronomical observations. Adapted from the Julian Date system, MJD subtracts 2,400,000.5 days to create a more manageable figure for scientists. The innovation allowed for simpler bookkeeping in astronomy, geophysics, and satellite tracking, reducing errors in day counting. Its offset date falls on midnight UT rather than noon, aligning timekeeping with the calendar day. The Modified Julian Day remains a standard reference in many scientific fields, illustrating the importance of precise temporal measurement in modern research.
1858
Julian Day
1947day.year
American scientists John Bardeen and Walter Houser Brattain observe the basic principles of the transistor, a key element for the electronics revolution of the 20th century.
John Bardeen and Walter Brattain demonstrate the operating principles of the first transistor, paving the way for the modern electronics era.
On November 17, 1947, American physicists John Bardeen and Walter Brattain conducted groundbreaking experiments at Bell Labs.
They observed how a small voltage applied to a germanium point-contact transistor could control a much larger current.
This achievement validated the transistor concept originally proposed by William Shockley earlier that year.
Transistors replaced bulky vacuum tubes and became fundamental building blocks for amplifiers and digital circuits.
Their innovation launched the electronics revolution, leading to computers, mobile phones, and countless modern devices.
For their work on semiconductors, Bardeen and Brattain were later awarded the Nobel Prize in Physics.
John Bardeen
Walter Houser Brattain
transistor
electronics
20th century
1970day.year
Luna programme: The Soviet Union lands Lunokhod 1 on Mare Imbrium (Sea of Rains) on the Moon. This is the first roving remote-controlled robot to land on another world and is released by the orbiting Luna 17 spacecraft.
The Soviet Union lands Lunokhod 1 on the Moon, marking the first remote-controlled rover to explore another world.
On November 17, 1970, the Soviet Luna 17 spacecraft delivered Lunokhod 1 to the Mare Imbrium region of the Moon. This pioneering rover was the first of its kind to be controlled from Earth and carried cameras, soil analysis tools, and radiation sensors. Over several months, Lunokhod 1 transmitted thousands of images and valuable scientific data about lunar terrain and composition. The mission demonstrated the feasibility of remote planetary exploration and influenced the design of future robotic rovers. Its success fueled the space race between the United States and the Soviet Union. The achievements of Lunokhod 1 remain a milestone in the history of space exploration.
Luna programme
Lunokhod 1
Mare Imbrium
Moon
Luna 17
2019day.year
The first known case of COVID-19 is traced to a 55-year-old man who had visited a market in Wuhan, Hubei Province, China.
The earliest identified COVID-19 case was recorded on November 17, 2019, in a man from Wuhan, China.
On November 17, 2019, a 55-year-old man who frequented a seafood market in Wuhan, Hubei Province, fell ill with respiratory symptoms later linked to a novel coronavirus.
This case is currently recognized as the first known instance of COVID-19 in humans.
Chinese health authorities initially investigated animal-to-human transmission sources at the market.
Subsequent cases revealed community spread, marking the beginning of a global health crisis.
Researchers and health officials worldwide scrambled to understand and contain the virus.
The event underscores the challenges of early detection and response to emerging infectious diseases.
2019
COVID-19
Wuhan, Hubei Province