Comet of the Week: Hale-Bopp C/1995 O1
Perihelion: 1997 April 1.14, q = 0.914 AU This week’s “Special Topics” presentation discusses, among other things, how the practice of discovering comets has changed over the years. Up until a couple of decades ago a rather large percentage of the known comets were discovered by amateur astronomers regularly scanning the skies with relatively small …
Special Topic: Discoveries and Surveys
Up until a few centuries ago, all the comets that were seen by human beings were “discovered” via the unaided eye. It is unlikely that there were ever any search efforts for these objects, rather, when they appeared they essentially revealed themselves to the people who were alive at that time. Probably the closest thing …
Scientists on their favorite science fiction
Tales of strange alien worlds, fantastic future technologies and bowls of sentient petunias have long captivated audiences worldwide. But science fiction is more than just fantasy in space; it can educate, inspire and expand our imaginations to conceive of the universe as it might be. We invited scientists to highlight their favourite science fiction novel …
QuizMe: The Red Planet
For more than 4,000 years, humans have been gazing upward at Mars. It was only in the past 60 years though that we’ve been able to study the Red Planet in much greater detail with the steady launch of missions to orbit and land upon the planet. Now it is your turn to test your …
Meteorites contain clues about geology of Mars
Despite the pandemic, NASA is on track to launch its Mars rover, Perseverance, this July from Cape Canaveral, Florida. Its central mission will be to search for evidence of previous life on Mars. An exciting component of the rover will be a specialized drill that will collect rock and soil samples to be cached on …
This Week in History: July 12-18
JULY 12, 2001: American astronomer Gary Melnick and his colleagues publish their discovery of water vapor around the old, evolved star CW Leonis, suggesting the presence of exocomets around that star. The subject of exocomets, including the importance of this discovery, is discussed in a previous “Special Topics” presentation. JULY 12, 2126: Comet 109P/Swift-Tuttle, the …
Comet of the Week: Shoemaker-Levy 9 1993e
Perihelion: 1994 April 18.57, q = 5.380 AU What could perhaps be considered the most successful search program for comets and near-Earth asteroids during the photographic era, i.e., before the advent of CCD-based comprehensive survey programs in the late 1990s, was conducted by renowned planetary geologist Eugene Shoemaker from 1982 to 1994. Usually once a …
Special Topic: Pluto
The discovery of the planet Uranus by British astronomer William Herschel in 1781 essentially doubled the size of the then-known solar system. During the years after Uranus’ discovery astronomers began to notice small discrepancies in its orbital motion, and at least two individuals – a young British astronomer named John Adams, and a French mathematician, …
Another delay slips launch of Mars 2020 to July 30
NASA’s flagship $2.4 Billion Mars 2020 Perseverance rover mission – dedicated to the search for signs of life beyond Earth – has suffered another significant delay to its launch from the Florida Space Coast to the Red Planet. The delay is a significant concern because NASA only has a narrow window until mid-August to launch …
This Week in History: July 5-11
JULY 5, 1687: British physicist Isaac Newton publishes his Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), usually known as the Principia, wherein he lays out what is now known as his Law of Universal Gravitation. Part of Newton’s work in the Principia was based upon his calculations of the Great Comet of 1680 …
Comet of the Week: 9P/Tempel 1
Perihelion: 2005 July 05.31, q = 1.506 AU With the various comprehensive survey programs that are currently operational, the discovery of previously-unknown short-period comets happens all the time these days. The situation was very different during the mid-19th Century, when only a handful of such objects were known, and the discovery of each one was …
Special Topic: Past Spacecraft Missions
The majority of what we know about the various planets and many of the other objects in our solar system has come from spacecraft missions sent to those bodies. Even with the best telescopes here on Earth many of these objects are little more than points of light in the sky, and it was only …
NASA renames HQ in honor of ‘Hidden Figure’ Mary Jackson
NASA Administrator Jim Bridenstine announced that the agency’s headquarters building in Washington, D.C., will be named in honor of Mary W. Jackson, the first African American female engineer at NASA. The ‘Hidden Figure’ story of Mary Jackson and other African-American women trailblazers that helped launch America’s first astronauts safely into space and back including Alan …
The future of space may be female
Only 566 people have ever travelled to space. Sixty-five of them, or about 11.5%, were women. NASA recently proclaimed it will put the “first woman and next man” on the Moon by 2024. Despite nearly 60 years of human spaceflight, women are still in the territory of “firsts”. Valentina Tereshkova, the first woman in space …
This Week in History: June 28-July 4
JUNE 28, 1911: A meteorite falls to the ground near the village of El Nakhla El Bahariya, Egypt. The Nakhla meteorite was one of the first-known meteorites determined to have come from Mars. A fragment of the Nakhla meteorite supposedly struck and killed a dog, although there has been no independent confirmation of this. “Martian …
Comet of the Week: Tebbutt 1861 II
Perihelion: 1861 June 12.01, q = 0.822 AU Two of the brighter comets of the latter half of the 19th Century were discovered by an Australian amateur astronomer, John Tebbutt, who for four decades essentially ran a one-man astronomical clearinghouse from his private observatory near Windsor, New South Wales. In addition to numerous astrometric observations …
Special Topic: The Tunguska Event and Other Recent Impacts
During the early morning hours on Tuesday, June 30, 1908, at around 7:17 A.M. local time, “something” entered the earth’s atmosphere near the Pacific coast of Asia, traveling northwestward. A few km above the surface of a largely uninhabited region of central Siberia, near the Stony Tunguska River some 90 km north-northwest of the village …
This Week in History: June 21-27
JUNE 22, 1978: U.S. Naval Observatory astronomer James Christy discovers Charon, Pluto’s first-known moon. Charon, the discovery of which would be confirmed with a series of transit and occultation events between it and Pluto that began in 1995, provided a major step in our understanding of Pluto’s size and physical nature. Pluto, its system of …
Comet of the Week: 2P/Encke
Perihelion: 2020 June 25.85, q = 0.337 AU In the early 19th Century the idea that comets might return to the inner solar system on a regular basis was still a bit of a novelty. This had been successfully demonstrated by the British astronomer Edmond Halley when the comet that now bears his name returned …
Special Topic: Orbits and Future Returns
“Ice and Stone 2020” participants have undoubtedly noticed that I have often discussed how this-or-that comet or asteroid will be returning to the inner solar system or passing by Earth at some point in the future, and perhaps have wondered how such things are determined. In principle, the processes by which such events are calculated …