Descriptive Astronomy 101


The largest planet in the Solar System
Fifth planet from the Sun
Gas giant
__________ times the diameter of Earth
__________ times the mass of Earth
__________ times the mass of all the other planets and satellites combined.


Jupiter rotates on its axis once every __________ hours
Rapid rotation results in a noticeably flattened oblate spheroid
Like the sun, Jupiter rotates more rapidly near the equator than it does at the poles.


Jupiter radiates about 2.5 times more heat than it receives from the Sun
Solid metal-rock core: diameter of approx. 24,000 km.
Metallic mixture of hydrogen and helium: 24,000 to 100,000 km
Liquid hydrogen and helium
Cloudy atmosphere, richer in ammonia and methane: down to 1,000 km deep below surface
Temperatures range from -130°C at cloud top to 20,000 K at the planet's center.


75% hydrogen and 25% helium by mass
90% hydrogen and 10% helium by number of atoms
Trace amounts of methane, ammonia, and other substances. Lack of water in the upper atmosphere
Water maybe concentrated in middle latitudes or confined to the planet's core
The upper atmosphere is separated into wide parallel bands due to:
Slight chemical and temperature differences between the bands are responsible for their different shades of yellow, brown, orange, and red.
The colors in atmosphere are also due in part to the release of phosphorous and the formation of acetylene.
Light-colored bands are referred to as __________.
Dark-colored bands are called __________.
Winds of more than 600 kph blow in opposite directions in adjacent bands
Winds are driven largely by the planet's internal heat.
Complex vortices occur in the boundary regions between the bands
Great Red Spot:
Smaller spots have been observed.

Magnetic Field

Jupiter has a powerful magnetic field
An immense magnetosphere:
Extends several million kilometers Sunward
Extends more than 650 million km outward

A Failed Star?

Jupiter has virtually the same elemental composition as the Sun
Jupiter would need at least __________ times more mass in order to become a brown dwarf
Jupiter would need __________ times more mass in order to have initiated nuclear reactions and shine as a star.


Jupiter has a faint ring system with four main components:
The rings are still being formed today.
Comet and meteor debris, accelerated by Jupiter's powerful gravitational field, smash into the inner four moons flinging dark-red surface material into space.


Jupiter has __________ known satellites in 4 groups.
Group 1: small/medium-sized, orbit at less than 200,000 km
The Galilean moons have orbits of 400,000 - 2 million km
Group 3: small-sized and orbits of 11 to 13 million km with inclinations of 26-29°.
Group 4: small-sized and high-inclination, retrograde orbits with radii of 19 to 28 mil. km.
All moons are tidally locked with the planet


The most volcanically active body in the Solar System
Sulfur-rich / frozen sulfur dioxide surface with hundreds of active volcanic calderas
Eruptions observed by Voyager and Galileo spacecraft.
Tidal forces between moons and Jupiter causes heating.
Flexes Io by as much as 100 m (max. tides Earth: 18 m)
This can generate temperatures as high as 2,000 K


Surface is smooth and flat, relief of only a few hundred meters.
Surface composition: water ice and sulfur compounds
Two types of terrain
Fracture patterns resemble those seen in the broken ice pack in Earth's Arctic and Antarctic Oceans.
Europa is heated by tidal forces and radioactive decay
Sub-surface ocean of liquid may exist on the moon


Largest satellite of Jupiter and of the entire solar system slightly large than Mercury
Differentiated internal structure
Ganymede has a magnetic field.
Younger, lighter regions marked with an extensive array of grooves and ridges of a tectonic origin
Extensive cratering indicates a surface age of 3 to 3.5 billion years.


Surface features: impact craters and rings.
Most heavily cratered of any object in the Solar System
Indicates a nearly complete lack of tectonic activity for over 4 billion years
Shows no signs of any resurfacing events since 3.8 billion years ago.
Surface composition:
Very thin atmosphere of ____________.

Jupiter Facts

Distance from Sun 5.20 AU
Distance from Sun 778.3 million km
Equatorial diameter 142,984 km
Equatorial diameter(Earth=1) 11.209
Mass (Earth=1) 317.9
Mean density 1.3 g/cm3
Axial period 9.8 hours
Axial inclination 3.1°
Orbital period 11.86 years
Orbital inclination 1.3°
Orbital eccentricity 0.048
Gravity at cloud-tops (Earth=1) 2.64
Escape velocity 60.2 km/s
Albedo 0.43