23 July 1972

The United States launches Landsat 1, the first Earth-resources satellite.

Landsat 1, officially known as the Earth Resources Technology Satellite 1 (ERTS-1), was the first satellite in the United States’ Landsat program and the world’s first Earth-resources satellite. It was launched on July 23, 1972, by NASA (National Aeronautics and Space Administration) in cooperation with the USGS (United States Geological Survey). The primary purpose of Landsat 1 was to gather valuable data about the Earth’s land surfaces from space.

Payload: Landsat 1 was equipped with several sensors and cameras to collect data in different spectral bands, including the Return Beam Vidicon (RBV) camera and the Multi-Spectral Scanner (MSS). These instruments allowed the satellite to capture images of the Earth’s surface with varying resolutions and spectral capabilities.

Orbit: The satellite operated in a sun-synchronous polar orbit, which means it circled the Earth at a fixed local solar time. This orbit allowed consistent lighting conditions during each pass over a given area, making it easier to compare images over time.

Mission Duration: Landsat 1 had a successful mission life and operated for about six years. Its mission concluded on January 6, 1978.

Image Resolution: The RBV camera provided high-resolution images with a ground resolution of about 80 meters, while the MSS instrument had a ground resolution of approximately 80 meters for bands 1-4 and 156 meters for band 5.

Data Collection: Landsat 1 played a crucial role in monitoring various Earth resources, including land use, agriculture, forestry, geology, water resources, and environmental changes. The data collected by Landsat 1 contributed significantly to the understanding of global land cover and land use changes.

Successors: Following the success of Landsat 1, several other Landsat missions were launched, each with improvements in technology and data collection capabilities. These subsequent missions, such as Landsat 2, Landsat 3, and so on, further advanced the understanding of Earth’s resources and environmental changes.

The Landsat program, with its series of satellites, has been pivotal in providing long-term, consistent, and valuable Earth observation data. The continuous data collection over several decades has been instrumental in monitoring changes in the Earth’s land surfaces, studying natural disasters, and supporting numerous scientific, environmental, and societal applications.

23 July 1995

Comet Hale–Bopp is discovered; it becomes visible to the naked eye on Earth nearly a year later.

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23 July 1942

The Treblinka extermination camp is opened.

On this day in 23 July 1942, the systematic deportation of Jews from the Warsaw ghetto begins, as thousands are rounded up daily and transported to a newly constructed concentration/extermination camp at Treblinka, in Poland.

On July 17, Heinrich Himmler, head of the Nazi SS, arrived at Auschwitz, the concentration camp in eastern Poland, in time to watch the arrival of more than 2,000 Dutch Jews and the gassing of almost 500 of them, mostly the elderly, sick and very young. The next day, Himmler promoted the camp commandant, Rudolph Hoess, to SS major and ordered that the Warsaw ghetto, be depopulated–a “total cleansing,” as he described it–and the inhabitants transported to what was to become a second extermination camp constructed at the railway village of Treblinka, 62 miles northeast of Warsaw.

Within the first seven weeks of Himmler’s order, more than 250,000 Jews were taken to Treblinka by rail and gassed to death, marking the largest single act of destruction of any population group, Jewish or non-Jewish, civilian or military, in the war. Upon arrival at “T. II,” as this second camp at Treblinka was called, prisoners were separated by sex, stripped, and marched into what were described as “bathhouses,” but were in fact gas chambers. T. II’s first commandant was Dr. Irmfried Eberl, age 32, the man who had headed up the euthanasia program of 1940 and had much experience with the gassing of victims, especially children. He compelled several hundred Ukrainian and about 1,500 Jewish prisoners to assist him. They removed gold teeth from victims before hauling the bodies to mass graves. Eberl was relieved of his duties for “inefficiency.” It seems that he and his workers could not remove the corpses quickly enough, and panic was occurring within the railway cars of newly arrived prisoners.

By the end of the war, between 700,000 and 900,000 would die at either Treblinka I or II. Hoess was tried and sentenced to death by the Nuremberg Tribunal. He was hanged in 1947.

23 July 1903

The Ford Motor Company sells its first car.


As any entrepreneur will tell you, paying your suppliers can be among the toughest challenges facing a start-up business. That’s as true now as it was in 1903, when 39-year-old motor racing enthusiast Henry Ford decided to strike out on his own.

In June that year, the Ford Motor Company was established. A thousand shares were split between 12 investors, with Ford, as vice-president and chief engineer, holding a 25.5% stake. But right from the get-go, the company was in dire straits.

The fledgling company depended on suppliers, including the Dodge brothers, to make car parts. These were assembled by a team of 40 engineers in a rented garage on Mack Avenue in Detroit. But Ford, who had yet to sell a single car, struggled to keep up with the payments.

Faced with the choice of walking away or doubling down, the Dodge brothers (who later founded their own famous car company) decided to throw their lot in with Ford. They agreed to write off $7,000, and extended a $3,000 six-month credit line in return for 10% of the company.

Not long after, things started to look up. The Ford Motor Company received its first order for three Model A cars, one of which was paid for upfront, while deposits totalling $1,320 were paid for the other two. That was just as well, seeing as the company had already blown through all but $223 of its $28,000 start-up capital.

“Who can’t afford a Fordmobile?”, asked an advert placed in the June edition of the Cycle and Automobile Trade Journal. Well, most people. The Model A came in two flavours: a four-seater ‘Tonneau’, priced at $850, while a sporty two-seater version, the ‘Runabout’, cost $750 – not cheap considering the average US salary in 1900 was only $438.

But Ernest Pfennig of Chicago was one of those who could, and on 23 July, he became the proud owner of a Ford. While the Model A was no runaway success, by October, the Ford Motor Company had managed to turn a $37,000 profit.

Ford and his engineers continued to tinker with his designs, and in 1908, the Model T went on sale. The ‘Tin Lizzie’ was a better hit with the motoring public, and safeguarded the Ford Motoring Company’s future in the years ahead.