the atmosphere of titan and mars

robertjford80

If Mars' mass is .1 Earths and the pressure of its atmosphere is .6 kPa then why is Titan's atmosphere 147 kpa when its mass is .02 Earths? Apparently mass is not much of a factor in determining a planet's atmosphere.

Vagn

Titan is a lot further away from the sun, so it can keep an atmosphere more easily than Mars can. Titan is also still geologically active so it can replenish its atmosphere through cryovolcanism, whereas (for the most part) Mars is geologically dead, with the only potential geological activity being whatever is responsible for the seasonal methane release.

robertjford80

neat. i had to look up cryovolcanism

A cryovolcano (colloquially known as an ice volcano) is a volcano that erupts volatiles such as water, ammonia or methane, instead of molten rock.[1] Collectively referred to as cryomagma or ice-volcanic melt,[1] these substances are usually liquids and form plumes, but can also be in vapour form. After eruption, cryomagma condenses to a solid form when exposed to the very low surrounding temperature. Cryovolcanoes form on icy moons, and possibly on other low-temperature astronomical objects (e.g., Kuiper belt objects).

Drakkith

Titan is also much colder than Mars or Earth, which allows it to retain more if it's atmosphere. Hotter atmospheres puff up more and are more easily eroded by the solar wind.

robertjford80

thanks, good to know

qraal

Titan and Mars have vastly different compositions, so they're not really comparable. We've very little data on what original mass of atmosphere might've existed on either object. We don't actually know if Mars had much more atmosphere than what we see today, and we don't know if Titan was always covered in such a thick atmosphere. We have many theories, but we go visit such worlds to refine our understanding.