Topic: Astronomy/Solar System
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๐ Timeline of the far future
While the future can never be predicted with absolute certainty, present understanding in various scientific fields allows for the prediction of some far-future events, if only in the broadest outline. These fields include astrophysics, which has revealed how planets and stars form, interact, and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which predicts how life will evolve over time; and plate tectonics, which shows how continents shift over millennia.
All projections of the future of Earth, the Solar System, and the universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must rise over time. Stars will eventually exhaust their supply of hydrogen fuel and burn out. Close encounters between astronomical objects gravitationally fling planets from their star systems, and star systems from galaxies.
Physicists expect that matter itself will eventually come under the influence of radioactive decay, as even the most stable materials break apart into subatomic particles. Current data suggest that the universe has a flat geometry (or very close to flat), and thus will not collapse in on itself after a finite time, and the infinite future allows for the occurrence of a number of massively improbable events, such as the formation of Boltzmann brains.
The timelines displayed here cover events from the beginning of the 11th millennium to the furthest reaches of future time. A number of alternative future events are listed to account for questions still unresolved, such as whether humans will become extinct, whether protons decay, and whether the Earth survives when the Sun expands to become a red giant.
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- "Timeline of the Far Future" | 2024-01-14 | 16 Upvotes 1 Comments
- "Timeline of the Far Future" | 2020-05-17 | 168 Upvotes 112 Comments
- "Timeline of the far future" | 2018-07-18 | 696 Upvotes 258 Comments
- "Timeline of the far future" | 2012-05-06 | 294 Upvotes 88 Comments
๐ Sweden Solar System
The Sweden Solar System is the world's largest permanent scale model of the Solar System. The Sun is represented by the Ericsson Globe in Stockholm, the largest hemispherical building in the world. The inner planets can also be found in Stockholm but the outer planets are situated northward in other cities along the Baltic Sea. The system was started by Nils Brenning and Gรถsta Gahm and is on the scale of 1:20 million.
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- "Sweden Solar System" | 2023-12-31 | 158 Upvotes 46 Comments
- "Sweden Solar System" | 2014-08-12 | 224 Upvotes 40 Comments
- "The Sweden Solar System" | 2011-02-15 | 195 Upvotes 26 Comments
๐ Wanggongchang Explosion
The Wanggongchang Explosion (Chinese: ็ๆญๅป ๅคง็็ธ), also known as the Great Tianqi Explosion (ๅคฉๅๅคง็็ธ), Wanggongchang Calamity (็ๆญๅป ไน่ฎ) or Beijing Explosive Incident in Late Ming (ๆๆๅไบฌ็็ธไบไปถ), was an unexplained catastrophic explosion that occurred on May 30 of the Chinese calendar in 1626 AD during the late reign of Tianqi Emperor, at the heavily populated Ming China capital Beijing, and had reportedly killed around 20,000 people. The nature of the explosion is still unclear to this day, as it is estimated to have released energy equivalent to about 10-20 kiloton of TNT, similar to that of the Hiroshima bombing.
Discussed on
- "Wanggongchang Explosion" | 2020-01-04 | 204 Upvotes 41 Comments
๐ Saturn's Hexagon
Saturn's hexagon is a persistent approximately hexagonal cloud pattern around the north pole of the planet Saturn, located at about 78ยฐN. The sides of the hexagon are about 14,500ย km (9,000ย mi) long, which is about 2,000ย km (1,200ย mi) longer than the diameter of Earth. The hexagon may be a bit more than 29,000ย km (18,000ย mi) wide, may be 300ย km (190ย mi) high, and may be a jet stream made of atmospheric gases moving at 320ย km/h (200ย mph). It rotates with a period of 10h 39m 24s, the same period as Saturn's radio emissions from its interior. The hexagon does not shift in longitude like other clouds in the visible atmosphere.
Saturn's hexagon was discovered during the Voyager mission in 1981, and was later revisited by Cassini-Huygens in 2006. During the Cassini mission, the hexagon changed from a mostly blue color to more of a golden color. Saturn's south pole does not have a hexagon, as verified by Hubble observations. It does, however, have a vortex, and there is also a vortex inside the northern hexagon. Multiple hypotheses for the hexagonal cloud pattern have been developed.
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- "Saturn's Hexagon" | 2024-02-29 | 71 Upvotes 7 Comments
๐ 319 Leona
319 Leona (provisional designation A920 HE), is a dark asteroid and tumbling slow rotator from the outermost regions of the asteroid belt, approximately 70 kilometers in diameter. It was discovered on 8 October 1891, by French astronomer Auguste Charlois at Nice Observatory in southwestern France. Any reference of its name to a person is unknown. On 12 December 2023 Leona will occult Betelgeuse as seen from southern Europe.
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- "319 Leona" | 2023-11-14 | 52 Upvotes 14 Comments
๐ Carrington Event
The Carrington Event was the most intense geomagnetic storm in recorded history, peaking from 1โ2 September 1859 during solar cycle 10. It created strong auroral displays that were reported globally and caused sparking and even fires in multiple telegraph stations. The geomagnetic storm was most likely the result of a coronal mass ejection (CME) from the Sun colliding with Earth's magnetosphere.
The geomagnetic storm was associated with a very bright solar flare on 1 September 1859. It was observed and recorded independently by British astronomers Richard Christopher Carrington and Richard Hodgsonโthe first records of a solar flare.
A geomagnetic storm of this magnitude occurring today would cause widespread electrical disruptions, blackouts, and damage due to extended outages of the electrical power grid.
Discussed on
- "Carrington Event" | 2024-05-12 | 43 Upvotes 16 Comments
๐ Robert Burnham Jr
Robert Burnham Jr. (June 16, 1931 โ March 20, 1993) was an American astronomer, best known for writing the classic three-volume Burnham's Celestial Handbook. He is the discoverer of numerous asteroids including the Mars crossing asteroid 3397ย Leyla, as well as six comets.
Burnham's late years were tragic; he died destitute and alone. However, he is remembered by a generation of deep sky observers for his unique contribution to astronomy, the Celestial Handbook. The main-belt asteroid 3467ย Bernheim was named in his honor.
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- "Robert Burnham Jr" | 2024-03-08 | 22 Upvotes 1 Comments
๐ Galilean Moons and Determination of Longitude
The Galilean moons (), or Galilean satellites, are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They are the most readily visible Solar System objects after Saturn, the dimmest of the classical planets; though their closeness to bright Jupiter makes naked-eye observation very difficult, they are readily seen with common binoculars, even under night sky conditions of high light pollution. The invention of the telescope enabled the discovery of the moons in 1610. Through this, they became the first Solar System objects discovered since humans have started tracking the classical planets, and the first objects to be found to orbit any planet beyond Earth.
They are planetary-mass moons and among the largest objects in the Solar System. All four, along with Titan, Triton, and Earth's Moon, are larger than any of the Solar System's dwarf planets. The largest, Ganymede, is the largest moon in the Solar System and surpasses the planet Mercury in size (though not mass). Callisto is only slightly smaller than Mercury in size; the smaller ones, Io and Europa, are about the size of the Moon. The three inner moons โ Io, Europa, and Ganymede โ are in a 4:2:1 orbital resonance with each other. While the Galilean moons are spherical, all of Jupiter's remaining moons have irregular forms because they are too small for their self-gravitation to pull them into spheres.
The Galilean moons are named after Galileo Galilei, who observed them in either December 1609 or January 1610, and recognized them as satellites of Jupiter in March 1610; they remained the only known moons of Jupiter until the discovery of the fifth largest moon of Jupiter Amalthea in 1892. Galileo initially named his discovery the Cosmica Sidera ("Cosimo's stars") or Medicean Stars, but the names that eventually prevailed were chosen by Simon Marius. Marius discovered the moons independently at nearly the same time as Galileo, 8 January 1610, and gave them their present individual names, after mythological characters that Zeus seduced or abducted, which were suggested by Johannes Kepler in his Mundus Jovialis, published in 1614. Their discovery showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by the naked eye. The discovery of celestial bodies orbiting something other than Earth dealt a serious blow to the then-accepted (among educated Europeans) Ptolemaic world system, a geocentric theory in which everything orbits around Earth.
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- "Galilean Moons and Determination of Longitude" | 2024-09-24 | 17 Upvotes 2 Comments
๐ Tardigrades on the Moon
On April 11, 2019, the Israeli spacecraft Beresheet crashed into the Moon during a failed landing attempt. Its payload included a few thousand tardigrades. Initial reports suggested they could have survived the crash landing. If any of them did survive, they would be the second animal species to reach the Moon, after humans.
We believe the chances of survival for the tardigrades... are extremely high.
๐ Superionic Water
Superionic water, also called superionic ice or ice XVIII, is a phase of water that exists at extremely high temperatures and pressures. In superionic water, water molecules break apart and the oxygen ions crystallize into an evenly spaced lattice while the hydrogen ions float around freely within the oxygen lattice. The freely mobile hydrogen ions make superionic water almost as conductive as typical metals, making it a superionic conductor. It is one of the 19 known crystalline phases of ice. Superionic water is distinct from ionic water, which is a hypothetical liquid state characterized by a disordered soup of hydrogen and oxygen ions.
While theorized for decades, it was not until the 1990s that the first experimental evidence emerged for superionic water. Initial evidence came from optical measurements of laser-heated water in a diamond anvil cell, and from optical measurements of water shocked by extremely powerful lasers. The first definitive evidence for the crystal structure of the oxygen lattice in superionic water came from x-ray measurements on laser-shocked water which were reported in 2019.
If it were present on the surface of the Earth, superionic ice would rapidly decompress. In May 2019, scientists at the Lawrence Livermore National Laboratory (LLNL) were able to synthesize superionic ice, confirming it to be almost four times as dense as normal ice and black in color.
Superionic water is theorized to be present in the mantles of giant planets such as Uranus and Neptune.
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- "Superionic Water" | 2024-02-03 | 17 Upvotes 1 Comments