Top 10 photos of Voyager 2 (Maijs 2024)
Io, saukts arī par Jupiteru I, ir iekšējais no četriem lielajiem pavadoņiem (Galilejas satelītiem), ko 1610. gadā ap Jupiteru atklāja itāļu astronoms Galileo. To droši vien pats tajā pašā gadā atklāja arī vācu astronoms Saimons Mariuss, kurš to nosauca Io vārdā Grieķu mitoloģija. Io ir vulkāniski aktīvākais ķermenis Saules sistēmā.
Jupiters: Io
Caur teleskopu no Zemes Io izskatās sarkanīgi oranžs, bet pārējie mēneši ir neitrāli. Io 's
Io griežas ar tādu pašu ātrumu, cik tas griežas ap Jupiteru (1,769 Zemes dienas), un tāpēc vienmēr tur to pašu seju pret Jupiteru. Tās gandrīz apļveida orbītā ir tikai 0,04 ° slīpums pret Jupitera ekvatoriālo plakni un rādiuss ir aptuveni 422 000 km (262 000 jūdzes). Orbīta ir spiesta būt nedaudz ekscentriskai ar gravitācijas rezonansi starp Io un Jovian moon Europa. Piespiedu ekscentriskums izraisa intensīvu Io plūdmaiņas sildīšanu - karsēšanu no iekšējās berzes, kas rodas nepārtrauktas satelīta izliekšanās dēļ - ar Jupitera jaudīgo gravitācijas lauku, kas ir enerģijas avots, kas darbina vulkānus.
Io is about 3,630 km (2,260 miles) in diameter, a little larger than Earth’s Moon. Its average density of about 3.55 grams per cubic cm is characteristic of rocks but not ices. Io has a very tenuous atmosphere, composed in large part of sulfur dioxide. Its surface is a startling, vividly coloured landscape of erupting volcanic vents, pools and solidified flows of lava, and deposits of sulfur and sulfur compounds. There is no evidence of impact craters on this geologically young surface. The volcanic flows are so extensive and frequent that they are resurfacing the entire satellite to a depth of several metres every few thousand years. Beneath the crust lies a layer of molten rock and a core of molten iron and iron sulfide approximately 1,800 km (1,110 miles) in diameter.
When the Voyager 1 spacecraft flew by Io on March 5, 1979, it observed nine active volcanoes ejecting fountains of fine particles several hundred kilometres into space. Observations at higher resolution by the Galileo spacecraft some 20 years later indicated that as many as 300 volcanoes may be active on the satellite at a given time. The silicate lava that is spewing out is extremely hot (approximately 1,900 K [3,000 °F, 1,630 °C]) and resembles lavas produced more than three billion years ago on Earth. Volcanic material ejected from the surface creates a toroidal (doughnut-shaped) cloud of charged particles that follows Io’s orbit and wraps part of the way around Jupiter. The ejected material contains mostly ionized atoms of oxygen, sodium, and sulfur with smaller amounts of hydrogen and potassium. As the satellite travels in its orbit, passing through the magnetic field of Jupiter, it produces an electric current of some five million amperes along a flux tube of spiraling electrons that links Io with the giant planet.
