spaceplasma:

Io

Looking like a giant pizza covered with melted cheese and splotches of tomato and ripe olives, Io is the most volcanically active body in the solar system. Volcanic plumes rise 300 km (190 miles) above the surface, with material spewing out at nearly half the required escape velocity.

A bit larger than Earth’s Moon, Io is the third largest of Jupiter’s moons, and the fifth one in distance from the planet.

Although Io always points the same side toward Jupiter in its orbit around the giant planet, the large moons Europa and Ganymede perturb Io’s orbit into an irregularly elliptical one. Thus, in its widely varying distances from Jupiter, Io is subjected to tremendous tidal forces. These forces cause Io’s surface to bulge up and down (or in and out) by as much as 100 m (330 feet)! Compare these tides on Io’s solid surface to the tides on Earth’s oceans. On Earth, in the place where tides are highest, the difference between low and high tides is only 18 m (60 feet), and this is for water, not solid ground!

This tidal pumping generates a tremendous amount of heat within Io, keeping much of its subsurface crust in liquid form seeking any available escape route to the surface to relieve the pressure. Thus, the surface of Io is constantly renewing itself, filling in any impact craters with molten lava lakes and spreading smooth new floodplains of liquid rock. The composition of this material is not yet entirely clear, but theories suggest that it is largely molten sulfur and its compounds (which would account for the varigated coloring) or silicate rock (which would better account for the apparent temperatures, which may be too hot to be sulfur). Sulfur dioxide is the primary constituent of a thin atmosphere on Io. It has no water to speak of, unlike the other, colder Galilean moons. Data from the Galileo spacecraft indicates that an iron core may form Io’s center, thus giving Io its own magnetic field.

Io’s orbit, keeping it at more or less a cozy 422,000 km (262,000 miles) from Jupiter, cuts across the planet’s powerful magnetic lines of force, thus turning Io into a electric generator. Io can develop 400,000 volts across itself and create an electric current of 3 million amperes. This current takes the path of least resistance along Jupiter’s magnetic field lines to the planet’s surface, creating lightning in Jupiter’s upper atmosphere.

As Jupiter rotates, it takes its magnetic field around with it, sweeping past Io and stripping off about 1,000 kg (1 ton) of Io’s material every second! This material becomes ionized in the magnetic field and forms a doughnut-shaped cloud of intense radiation referred to as a plasma torus. Some of the ions are pulled into Jupiter’s atmosphere along the magnetic lines of force and create auroras in the planet’s upper atmosphere. It is the ions escaping from this torus that inflate Jupiter’s magnetosphere to over twice the size we would expect.

Discovery:
Io was discovered on 8 January 1610 by Galileo Galilei. The discovery, along with three other Jovian moons, was the first time a moon was discovered orbiting a planet other than Earth. The discovery of the four Galilean satellites eventually led to the understanding that planets in our solar system orbit the sun, instead of our solar system revolving around Earth. Galileo apparently had observed Io on 7 January 1610, but had been unable to differentiate between Io and Europa until the next night.

How Io Got its Name:
Galileo originally called Jupiter’s moons the Medicean planets, after the Medici family and referred to the individual moons numerically as I, II, III, and IV. Galileo’s naming system would be used for a couple of centuries.

It wouldn’t be until the mid-1800s that the names of the Galilean moons, Io, Europa, Ganymede, and Callisto, would be officially adopted, and only after it became apparent that naming moons by number would be very confusing as new additional moons were being discovered.

Io was originally designated Jupiter I by Galileo because it is the first satellite of Jupiter. Io is named for the daughter of Inachus, who was raped by Jupiter. Jupiter, in an effort to hide his crime from his wife, Juno, transformed Io into a heifer.

Credit: NASA/JPL

(via itsfullofstars)

jtotheizzoe:

geneticist:

After the Pluto’s demotion from planet-status, astrophysicist Neil DeGrasse Tyson received hate mail from thousands of elementary school children. Images via PBS

Well kids, I guess you can add me to the Pluto-hatin’ club. I’ve got your back Dr. Tyson!

If Pluto landed on Earth, it would only stretch from California to Kansas. It’s smaller than our own Moon and half ice. It orbits more like a comet than a planet. It has more in common with the members of the icy and distant Kuiper belt than the larger planets. In fact, it could take the cake as Kuiper king, Emperor of dwarf planets. Don’t hate me, folks. Science is an ever-evolving tapestry, and that tapestry has 8 planets :)

Ouch, hate mail from elementary school kids… That’s gotta suck. But whatcha gonna do, Pluto definite isn’t a planet. The truth hurts, kids.

(via we-are-star-stuff)

unknownskywalker:

ALMA Sheds Light on Planet-Forming Gas Streams

Left: observations made with the Atacama Large Millimeter/submillimeter Array (ALMA) telescope of the disc of gas and cosmic dust around the young star HD 142527, showing vast streams of gas flowing across the gap in the disc. These are the first direct observations of these streams, which are expected to be created by giant planets guzzling gas as they grow, and which are a key stage in the birth of giant planets.

The dust in the outer disc is shown in red. Dense gas in the streams flowing across the gap, as well as in the outer disc, is shown in green. Diffuse gas in the central gap is shown in blue. The gas filaments can be seen at the three o’clock and ten o’clock positions, flowing from the outer disc towards the centre.

The dense gas observed is HCO⁺, and the diffuse gas is CO. The outer disk is roughly two light-days across. If this were our own Solar System, the Voyager 1 probe — the most distant manmade object from Earth — would be at approximately the inner edge of the outer disk.

Right: artist’s impression of the disc and gas streams, for illustration.

thenewenlightenmentage:

New Images Show a “Living” Mars

Over the years, scientists have found evidence revealing that an ocean may have covered parts of the Red Planet billions of years ago. Others suggest that a future terraformed Mars could be lush with oceans and vegetation. In either scenario, what would Mars look like as a planet alive with water and life? By combining data from several sources — along with a bit of creative license — software engineer Kevin Gill has created some gorgeous images showing concepts of what a “living Mars” might look like from orbit, turning the Red Planet into its own version of the Blue Marble.

Continue Reading

Fun to imagine.

sciencespook:

This is our sun. The heart of the solar system, just another star in a sea of stars. -Brian Cox

(Source: sciencesoup, via aninterestingdebate)