emc wrote:It is not known if Jupiter has a solid surface. How do scientists determine the mass and density if we can't probe or "see" to the core?
I can ask you a similar question: "How do scientists determine the mass and density of our sun, if they can't see whether the sun has a solid core?"
The answer is e.g. Kepplers 3rd law:
a³/P² = G (M + m) / (4 π²)
where a is the semi half axis of the orbit of a small object with mass m around a heavy object with mass M, P is the period of revolution of m around M and G is the gravitational constant. &3960; needs no formal introduction.
For instance by using the earths data of the orbit oround our sun, we can determine M+m and since m is small compared to M, we find M: the solar mass.
Similarly by studying the orbit of our moon, we can determine the mass of the earth.
By studying the orbits of moons of Jupiter one can determine the mass of Jupiter and the moon. Since the moon has a negligible mass, we know Jupiters mass.
"Now i got you" i hear you say: how do we know the distance from the earth to the sun or to our moon? Basically by parallax. Stellar ocultations by the moon determine the distance from the earth to the moon. Observations of a transition of Venus over the suns limb, just like a few years ago, was the major opportunity to measure the distances in our solar system. In the latter half of the last century radar techniques took over that role.
To do the math on the earth's orbit:
a = 1.5E11 m. P = 3.16E7 s. 4π² = 39.5. G = 6.67E-11 m³/(kg s²). M+m = 2E30 kg. Look in your textbook on astronomy or Google the solar mass on the net and you will find similar values.
[quote="emc"]It is not known if Jupiter has a solid surface. How do scientists determine the mass and density if we can't probe or "see" to the core? [/quote]
I can ask you a similar question: "How do scientists determine the mass and density of our sun, if they can't see whether the sun has a solid core?"
The answer is e.g. Kepplers 3rd law:
a³/P² = G (M + m) / (4 π²)
where a is the semi half axis of the orbit of a small object with mass m around a heavy object with mass M, P is the period of revolution of m around M and G is the gravitational constant. &3960; needs no formal introduction.
For instance by using the earths data of the orbit oround our sun, we can determine M+m and since m is small compared to M, we find M: the solar mass.
Similarly by studying the orbit of our moon, we can determine the mass of the earth.
By studying the orbits of moons of Jupiter one can determine the mass of Jupiter and the moon. Since the moon has a negligible mass, we know Jupiters mass.
"Now i got you" i hear you say: how do we know the distance from the earth to the sun or to our moon? Basically by parallax. Stellar ocultations by the moon determine the distance from the earth to the moon. Observations of a transition of Venus over the suns limb, just like a few years ago, was the major opportunity to measure the distances in our solar system. In the latter half of the last century radar techniques took over that role.
To do the math on the earth's orbit:
a = 1.5E11 m. P = 3.16E7 s. 4π² = 39.5. G = 6.67E-11 m³/(kg s²). M+m = 2E30 kg. Look in your textbook on astronomy or Google the solar mass on the net and you will find similar values.