2037 Astro Spring 07, Lecture 23
Possibility of Life on Jupiter
Hydrogen-rich environment (similar to the conditions on the primitive Earth), however, Jupiter, 318 times Earths mass, keeps hydrogen from escaping, i.e., Jupiter has a huge number of hydrogen atoms to combine with any elements or molecular fragments. It is impossible for Jupiter to manufacture complex molecules. On the contrary, Earth rapidly lost its hydrogen, leading to an environment more suitable for the evolution of a complex biochemistry Jupiter does not have a solid surface, and thus it has no likely microenvironments, such as Earths tidal pools, in which the products from chemical reactions in the atmosphere could accumulate, nor does Jupiter offer the opportunity for chemical reactions to be catalyzed by soil surfaces Another problem is caused by the vertical convection in Jupiters atmosphere. The heat inside (above 700C) could also destroy complex molecules. The Great Red Spot is perhaps stable enough to allow formation of complex molecules in Jupiters upper atmosphere
Jupiters Internal Structure, deduced from spacecraft measurements and theoretical modeling
Jupiters Four Large Moons
Four moons names were from Jupiters four loves With solid surfaces (Ganymede, and Callisto are, respectively, larger than and about the same size as Mercury) They imitate the gross characteristics of the solar system: the innermost moons, Io and Europa, have densities of matter similar to those of the inner planets, while Ganymede and Callisto represent the outer planets, with low densities implying a high abundance of ice All four moons have been intensively studied by Voyager spacecraft in 1979 and the Galileo orbitor during the late 1990s Many new discoveries: Lack of large impact craters on Callisto, evidence for plate motions of the crust of Ganymede, a complex network of linear features on Europa, and the active volcanoes of Io
The Four Large Satellites of Jupiter
Solar Planet Properties
12757 km
Rings and Satellites Around Jovian Planets
Within a certain distance of a planet, called the Roche Limit, objects cannot grow larger by gravitational attraction because the gravitational force exerted by the planet on two objects in contact exceeds the gravitational force between the two objects. Outside the Roche limit, objects can accumulate into larger bodies by using their gravitational forces, which will be strong enough to hold them together.
The vertical structure of Saturns atmosphere contains several cloud layers, like Jupiter, but Saturns weaker gravity results thicker in layers and a more uniform appearance
Saturns atmosphere consists of 92.4% molecular hydrogen and 7.4% helium, with traces of methane and ammonia
Saturns Cloud Structure
There are stable east-west zonal flow, the wind speed is considerably greater than on Jupiter and shows fewer east-west alternations The equatorial eastward jet stream reaches a speed of 1500 km/hr
Saturns Largest Moon, Titan
Visible image taken with Voyager 1 Infrared image with the Hubble Space telescope shows some thermal features
Titan, larger than Mercury and roughly half the size of Earth, has an atmosphere Due to relatively low atmospheric temperature (85 K), it can keep its atmosphere stable, the pressure is 1.5 times the sea level pressure on Earth The atmosphere includes mostly nitrogen, and methane, and also rich in organic molecules, allowing study of chemical reactions in the early solar system
Artists Imagination of the view from Titan
Fuel (methane) is everywhere, but lacks oxygen to burn it
Images from the Huygens probe January 14th, 2005
Confirmed the presence of large bodies of liquid
Uranus and its Atmosphere
Image-enhanced view of Uranus highlights some of its atmospheric features and its surrounding ring taken by Voyager 2
Few clouds exist in Uranuss cold upper atmosphere Clouds of the kind found on Jupiter and Saturn are found only at lower, warmer atmospheric levels The absence of high-level clouds means we must look deep into the planets atmosphere, the bands and spots that characterize flow patterns on ot...