Hendrik Christoffel van de Hulst was born on November 19th 1918 in Utrecht, the Netherlands. He predicted theoretically the 21-cm (8.2inch) radio waves produced by interstellar hydrogen atoms. His calculations later were of great help in mapping the Milky Way Galaxy, and were the basis for radio astronomy during its early development.
In addition to his work in radio astronomy, he made important contributions to the understanding of light scattering by small particles, the solar corona, and interstellar clouds. From the 1960’s Van de Hulst became a leader in international and European space research and development efforts.
Van de Hulst died on July 31st 2000 aged 81.
In the evening sky on Thursday, November 15, the waxing, slightly gibbous moon will be situated 3 degrees (or 3 finger widths) to the lower right of reddish planet Mars. The orbital path of the moon will carry it closer to Mars through the evening. The duo will set in the west at about midnight local time. Observers in most of Antarctica, the Falkland Islands, and southern South America will see the moon occult Mars at about 06:00 UT.
Zond 6 was launched on November 10th 1968, and flew around the Moon on November 14th. It managed to take photos of both the near side and far side of the moon, but only one negative was recovered from the camera container.
Zond 6 used a reletively uncommon technique called “skip reentry”, to shed velocity upon returning to Earth. A few hours before reentry, on 17 November 1968, a faulty O-ring rubber gasket caused the cabin to depressurise, killing all the animal test subjects aboard. Also Zond 6’s parachutes deployed too early and it crashed in Kazakhstan, not far from the designated landing area.
For propaganda reasons the Soviet Union claimed the flight was a complete success.
Zond 6 was a precursor to a manned circumlunar flight which the Soviets hoped could occur in December 1968, meaning the USSR would be the first nation to have a manned circumlunar flight. However the delays caused by the failure of Zond 6 meant it was the United States with Apollo 8 which was the first nation to achieve this.
Appropriately enough this year’s Dark Matter Day will take place on Halloween. Across Britain, the US and Europe, talks, demonstrations and parties highlighting the search for dark matter will be held on 31st October. “I don’t think you could pick a better date to celebrate a hunt for something that is as ephemeral and mysterious as dark matter,” said physicist Chamkaur Ghag, of University College London. “We can see its effects, but cannot detect it directly. It is the ultimate in ghostly phenomena.”
The existence of dark matter has both been controversial and frustrating to modern physicists. Dark Matter cannot be observed, but is inferred because of galaxies that rotate too quickly to hold themselves together. Approximately 85% of the universe’s total mass is believed to be made up of dark matter.
“Ever since Coperincus, we have known we are not located anywhere special in the universe,” said astronomer royal Martin Rees. “But now it transpires we are not even made of the dominant stuff in the cosmos. Most of it is made up of material from the dark side, the side we cannot yet see.”
Without dark matter there would be nothing to hold galaxies together, and hence no stars, no planets and no life, which is what has led scientists to promote the idea of Dark Matter Day.
Source: The Guardian: