Topic: Astronomy (Page 5)
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π The Nebra sky disk
The Nebra sky disk is a bronze disk of around 30 centimeters (11Β 3β4Β in) diameter and a weight of 2.2 kilograms (4.9Β lb), having a blue-green patina and inlaid with gold symbols. These symbols are interpreted generally as the Sun or full moon, a lunar crescent, and stars (including a cluster of seven interpreted as the Pleiades). Two golden arcs along the sides, interpreted to mark the angle between the solstices, were added later. A final addition was another arc at the bottom surrounded with multiple strokes (of uncertain meaning, variously interpreted as a Solar Barge with numerous oars, the Milky Way, or a rainbow).
The disk is attributed to a site in present-day Germany near Nebra, Saxony-Anhalt, and dated by Archaeological association to c.Β 1600 BC. Researchers suggest the disk is an artifact of the Bronze Age Unetice culture.
The style in which the disk is executed was unlike any artistic style then known from the period, with the result that the object was initially suspected of being a forgery, but is now widely accepted as authentic.
The Nebra sky disk features the oldest concrete depiction of the cosmos yet known from anywhere in the world. In June 2013 it was included in the UNESCO Memory of the World Register and termed "one of the most important archaeological finds of the twentieth century."
Discussed on
- "The Nebra sky disk" | 2015-01-31 | 57 Upvotes 3 Comments
π Carrington Event
The Carrington Event was the most intense geomagnetic storm in recorded history, peaking from 1β2 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 Hodgsonβthe 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
π Tell HN: Happy Solstice
The winter solstice, hiemal solstice or hibernal solstice, also known as midwinter, occurs when one of the Earth's poles has its maximum tilt away from the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, when the Sun is at its lowest daily maximum elevation in the sky. At the pole, there is continuous darkness or twilight around the winter solstice. Its opposite is the summer solstice.
The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (usually 21 or 22 December) and in the Southern Hemisphere, this is the June solstice (usually 20 or 21 June). Although the winter solstice itself lasts only a moment, the term sometimes refers to the day on which it occurs. Other names are "midwinter", the "extreme of winter" (Dongzhi), or the "shortest day". Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter, but today in some countries and calendars, it is seen as the beginning of winter. In meteorology, winter is reckoned as beginning about three weeks before the winter solstice.
Since prehistory, the winter solstice has been seen as a significant time of year in many cultures, and has been marked by festivals and rituals. It marked the symbolic death and rebirth of the Sun. The seasonal significance of the winter solstice is in the reversal of the gradual lengthening of nights and shortening of days.
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- "Tell HN: Happy Solstice" | 2009-12-21 | 37 Upvotes 19 Comments
π Tell HN: Perseids: "Last Chance" for Best Meteor Viewing Tonight
The Perseids are a prolific meteor shower associated with the comet SwiftβTuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus.
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- "Tell HN: Perseids: "Last Chance" for Best Meteor Viewing Tonight" | 2009-08-12 | 20 Upvotes 13 Comments
π Canadian Hydrogen Intensity Mapping Experiment
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is an interferometric radio telescope at the Dominion Radio Astrophysical Observatory in British Columbia, Canada which consists of four antennas consisting of 100 x 20 metre cylindrical parabolic reflectors (roughly the size and shape of snowboarding half-pipes) with 1024 dual-polarization radio receivers suspended on a support above them. The antenna receives radio waves from hydrogen in space at frequencies in the 400β800 MHz range. The telescope's low-noise amplifiers are built with components adapted from the cellphone industry and its data are processed using a custom-built FPGA electronic system and 1000-processor high-performance GPGPU cluster. The telescope has no moving parts and observes half of the sky each day as the Earth turns. It has also turned out to be a superior instrument for observing the recently discovered phenomenon of fast radio bursts (FRBs).
CHIME is a partnership between the University of British Columbia, McGill University, the University of Toronto and the Canadian National Research Council's Dominion Radio Astrophysical Observatory. A first light ceremony was held on 7 September 2017 to inaugurate the commissioning phase.
Discussed on
- "Canadian Hydrogen Intensity Mapping Experiment" | 2021-03-14 | 27 Upvotes 6 Comments
π Eltanin impact
The Eltanin impact is thought to be an asteroid impact in the eastern part of the South Pacific Ocean during the Pliocene-Pleistocene boundary around 2.51βΒ±β0.07β million years ago. The location was at the edge of the Bellingshausen Sea 1,500Β km (950Β mi) southwest of Chile. The asteroid was estimated to be about one to fourΒ km (0.6 to 2.5Β mi) in diameter and the impact would have left a crater approximately 35Β km (22Β mi) across.
Discussed on
- "Eltanin impact" | 2019-07-27 | 25 Upvotes 3 Comments
π Ali Qushji
Ala al-DΔ«n Ali ibn Muhammed (1403 β 16 December 1474), known as Ali Qushji (Ottoman Turkish/Persian language: ΨΉΩΫ ΩΩΨ΄ΪΫ, kuΕΓ§u β falconer in Turkish; Latin: Ali Kushgii) was an astronomer, mathematician and physicist originally from Samarkand, who settled in the Ottoman Empire some time before 1472. As a disciple of Ulugh Beg, he is best known for the development of astronomical physics independent from natural philosophy, and for providing empirical evidence for the Earth's rotation in his treatise, Concerning the Supposed Dependence of Astronomy upon Philosophy. In addition to his contributions to Ulugh Beg's famous work Zij-i-Sultani and to the founding of Sahn-Δ± Seman Medrese, one of the first centers for the study of various traditional Islamic sciences in the Ottoman caliphate, Ali KuΕΓ§u was also the author of several scientific works and textbooks on astronomy.
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- "Ali Qushji" | 2017-03-26 | 19 Upvotes 8 Comments
π Solar eclipse of August 12, 2026
A total solar eclipse will occur at the Moon's descending node of the orbit on Wednesday, August 12, 2026, 2 days past perigee (Perigee on Monday, August 10, 2026), in North America and Europe. The total eclipse will pass over the Arctic, Greenland, Iceland, Atlantic Ocean and northern Spain. The points of greatest duration and greatest eclipse will be just 45Β km off the western coast of Iceland by 65Β°10.3' N and 25Β°12.3' W, where the totality will last 2m 18.21s. It will be the first total eclipse visible in Iceland since June 30, 1954, also Solar Saros series 126 (descending node), and the only one to occur in the 21st century as the next one will be in 2196.
Occurring only 2.3 days after perigee (Perigee on August 10, 2026), the Moon's apparent diameter will be larger. Lunar Perigee will occur on Monday, August 10, 2026, two days before the total solar eclipse.
The total eclipse will pass over northern Spain from the Atlantic coast to the Mediterranean coast as well as the Balearic Islands. The total eclipse will be visible from the cities of Valencia, Zaragoza, Palma and Bilbao but both Madrid and Barcelona will be just outside the path of totality.
The last total eclipse in continental Europe occurred on March 29, 2006 and in continental part of European Union it occurred on August 11, 1999. The last total solar eclipse happened in Spain on August 30, 1905 and followed a similar path across the country. The next total eclipse visible in Spain will happen less than a year later on 2 August 2027. A partial eclipse will cover more than 90% of the area of the sun in Ireland, Great Britain, Portugal, France, Italy, the Balkans and North Africa and to a lesser extent in most of Europe, North Africa and North America.
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- "Solar eclipse of August 12, 2026" | 2023-10-14 | 21 Upvotes 6 Comments
π Ton 618, 40B solar mass
TON 618 (short for Tonantzintla 618) is a hyperluminous, broad-absorption-line, radio-loud quasar and Lyman-alpha blob located near the border of the constellations Canes Venatici and Coma Berenices, with the projected comoving distance of approximately 18.2 billion light-years from Earth. It possesses one of the most massive black holes ever found, at 40 billion Mβ.
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- "Ton 618, 40B solar mass" | 2023-05-05 | 22 Upvotes 4 Comments
π 774β775 carbon-14 spike
The 774β775 carbon-14 spike is an observed increase of 1.2% in the concentration of carbon-14 isotope in tree rings dated to 774 or 775, which is about 20 times as high as the normal background rate of variation. It was discovered during a study of Japanese cedar trees, with the year of occurrence determined through dendrochronology. A surge in beryllium isotope 10
Be, detected in Antarctic ice cores, has also been associated with the 774β775 event. It is known as the Miyake event or the Charlemagne event and it produced the largest and most rapid rise in carbon-14 ever recorded.
The event appears to have been global, with the same carbon-14 signal found in tree rings from Germany, Russia, the United States, Finland and New Zealand.
The signal exhibits a sharp increase of around 1.2% followed by a slow decline (see Figure 1), which is typical for an instant production of carbon-14 in the atmosphere, indicating that the event was short in duration. The globally averaged production of carbon-14 for this event is calculated as Q = 1.3Γ108 Β± 0.2Γ108 atoms/cm2.
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- "774β775 carbon-14 spike" | 2021-06-23 | 23 Upvotes 1 Comments