Option 1: One tenth of the solar mass. This means that the mass of Jupiter is 1/10th of the mass of our Sun. This option suggests that Jupiter is much smaller and less massive than the Sun, which is incorrect.

Option 2: One thousandth of the solar mass. This means that the mass of Jupiter is 1/1000th of the mass of our Sun. This option is the correct answer provided. It accurately states that Jupiter is much smaller and less massive compared to the Sun.

Option 3: One hundredth of the solar mass. This means that the mass of Jupiter is 1/100th of the mass of our Sun. This option is incorrect, as it suggests that Jupiter is larger and more massive than it actually is.

Option 4: Half the solar mass. This means that the mass of Jupiter is half of the mass of our Sun. This option is incorrect, as Jupiter`s mass is much smaller compared to the Sun.

Therefore, the correct answer is option 2, which states that the mass of Jupiter is one thousandth of the solar mass.