# Question Regarding Determining the Mass of Venus

• I
• astropi
In summary, the conversation discusses the standard gravitational parameter of Venus and the discrepancy in values calculated using different units. The paper by A. S. Konopliv, W. B. Banerdt, and W. L. Sjogren lists values for the parameter, but the speaker is having trouble getting the correct value due to a misunderstanding of the units. The correct units are km^3 s^-2, which explains the 9 orders of magnitude difference.
astropi
TL;DR Summary
Trying to determine the "strange" units this paper is using.
Venus is in the news! I looked up this well-regarded paper by A. S. Konopliv, W. B. Banerdt, and W. L. Sjogren
Venus Gravity: 180th Degree and Order Model
They list values for GM (see attached picture), such as
GM 324858.63 ± 0.01
so in principle calculating M should be trivial. The problem is I am orders of magnitude off from the actual value. I thought perhaps they were using cgs units, but that gives a value for M that is 15 orders of magnitude off. Clearly, I'm missing something. I looked through the paper and couldn't find anything that clarified the situation. Anyone know the units they are using or what I am missing? Thanks in advance.

Edit: Just to clarify, this is NOT for homework or any school related activity. Simply my own understanding.

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Wikipedia said:
In celestial mechanics, the standard gravitational parameter μ of a celestial body is the product of the gravitational constant G and the mass M of the body.

For several objects in the Solar System, the value of μ is known to greater accuracy than either G or M.The SI units of the standard gravitational parameter are ##m^3 s^{−2}##. However, units of ##km^3 s^{−2}## are frequently used in the scientific literature and in spacecraft navigation.
That's your 9 orders of magnitude difference.

stefan r and astropi
Thanks Bandersnatch, in retrospect that should have been pretty obvious!

## 1. How is the mass of Venus determined?

The mass of Venus is determined through the use of Newton's law of universal gravitation, which states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. By measuring the orbital period and distance of Venus around the Sun, scientists can calculate its mass.

## 2. What is the mass of Venus?

The mass of Venus is approximately 4.867 × 10^24 kilograms, which is about 81.5% of the Earth's mass.

## 3. How does Venus' mass compare to other planets in the solar system?

Venus has the second highest mass of any planet in the solar system, behind only Jupiter. It is significantly smaller than Jupiter, but larger than all other planets including Earth.

## 4. Can the mass of Venus change over time?

The mass of Venus is relatively stable and does not change significantly over time. However, small changes may occur due to the accumulation of dust and debris from comets and meteoroids, or the loss of gases from its atmosphere.

## 5. Why is it important to determine the mass of Venus?

Knowing the mass of Venus is important for understanding the formation and evolution of our solar system. It also helps scientists study the planet's internal structure and composition, as well as its gravitational influence on other objects in the solar system.

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