Jupiter - Astroman

Jupiter

Own image: Moons visible Io, Europa and Ganymede respectively (from L to R).
Equipment: Celestron C8 asgt, Meade DSI II,Barlow lens
Technical details: 0.1250 sec exposures, 200 stacked and registered PP in Cs4

Jupiter

The largest and fifth planet from the sun is named after the Roman God, Jupiter (Jove), and is by far one of the most 
heavily studied Gas Giants (Jupiter as well as Saturn, Uranus, Neptune which are also known as Jovian planets due to their 
simalarities and relatively large sizes). The most impressive thing about Jupiter is it's massive size, with an equatorial 
diameter of  142,982km - meaning that if you put all the other planets together Jupiter would still be two and a half 
times larger. Despite this, Jupiter has only a density of around 1.326 g/cm³  but a mass of 1.8986×10²⁷ kg.

Atmosphere

Jupiter's atmosphere in mainly made up from gas composed of around 89% hydrogen, 10% heilum with the rest made 
from trace gases such as methane. This mix is roughly of solar proportions (meaning similar to the sun's composition,  
unlike Earth). Jupiter's atmosfere is divided into cloud layers (belts) such as the SEB (South Equitorial Band) which is 
usually the darkest belt, the NEB (North Equatorial Belt), the STB etc. 

The most impressive feature is Jupiter's famous Great Red Spot (accompanied by Red Spot Jr), which is a giant, 
anticyclonic storm which has lasted for at least 340 years - if not more. The red spot is changing in shape from oblong 
to a more circular shape which has become even more prominent in recent years.

These all give Jupiter one of the most active and spectacular atmosferes of the gas giants. It is a marvel to look at through
an 8-inch, or larger, telescope and has delivered breath-taking images from missons such as Galileo 1989-2003(NASA), the New Horizons
mission not to mention the Hubble space telescope.


Satellites

Jupiter possesses around 28 known satellites, four of which - Callisto, Europa, Ganymede and Io - were observed by 
Galileo Galilei as long ago as 1610. These moons (called the Galilean moons) are easily visable using a small telescope and 
resemble stars, as they are too small and distant for average telescopes to resolve in any detail. 





1. Callisto
Callisto is the third largest moon in the Solar system (after Ganymede and Titan). Callisto's surface is highly impacted 
and rocky suggesting a lack of an atmosphere (hence no 'shielding' from solar debris), but a analysis by the Galileo probe 
detected a very thin atmosphere of carbon dioxide, probably replenished by under-surface ice.





2. Europa 
Europa is slightly smaller than Earth's own moon, making it the 6th largest in the solar system. Contrary to Callisto, 
Europa is an extremely smooth moon and  one of the smoothest objects in the solar system. Europa's most well known 
feature is it's ice-covered surface and the possibility of a liquid body underneath implies that extra-terrestrial 
life might exist there. Europa is currently the most probable host for life in the Solar system - unlike Mars where it is thought 
that no life exists, at least currently.





3. Ganymede
Ganymede is the Solar system's largest moon and greater in size (though not in mass) than the planet Mercury. 
Ganymede is the only moon in the Solar system known to have an active magnetosphere. Ganymede's surface is also 
relatively impacted  but the surface resembles a patchwork of new and old areas.





4. Io
Io is the fourth largest moon in the solar system but the most geologically active, with over 400 active volcanos.
This highly observed moon has a very dynamic surface as seen in images from the Galileo probe in 1999 and New 
Horizons in 2007, where in the time-frame separating the two missons major variations occurred.

More information:
http://sse.jpl.nasa.gov/planets/profile.cfm?Object=Jupiter