Deep in the interiors of the giant planets, water is still a liquid even though the temperatures are tens of thousands of degrees above the boiling point of water. This can happen because a. the density inside the giant planets is so high. b. the pressure inside the giant planets is so high. c. the outer Solar System is so cold. d. space has very low pressure.

In the deep interiors of giant planets like Jupiter and Saturn, the pressure is exceptionally high. This immense pressure can influence the physical state of materials in surprising ways. Normally, water boils at 100°C (212°F) at the pressure of 1 atmosphere (standard sea-level pressure on Earth). However, inside giant planets, the pressure is millions of times greater.

When the pressure increases, it prevents the water molecules from escaping and turning into vapor, despite the temperatures being extremely high. This is why, even at temperatures tens of thousands of degrees above its boiling point, water can still remain in a liquid state under such high pressures. The high-pressure environment presses the water molecules together so tightly that they cannot transition into a gas.

Understanding the influence of high pressure helps to explain many phenomena occurring within these massive celestial bodies. It sheds light on the unique conditions that exist within giant planets, which are vastly different from those on Earth.

In the context of the interiors of giant planets, density alone does not explain why water remains in a liquid state at such high temperatures. Density, which measures how closely packed the molecules of a substance are, can influence the behavior of materials but isn’t the sole factor at play here.

While high density might support the existence of liquid water under certain conditions, it is the extremely high pressure that is the critical factor keeping water in a liquid state within a giant planet. In fact, both high pressure and high density often occur together within the massive interiors of these planets. Still, it is the pressure that directly combats the high thermal energy that would otherwise turn water into vapor.

Therefore, although the density is remarkably high deep inside giant planets, we attribute the liquid state of water at extreme temperatures primarily to the high-pressure conditions rather than to density alone.

The boiling point of water is typically 100°C (212°F) at sea-level atmospheric pressure. However, this boiling point is not set in stone; it changes with varying pressure conditions.

Inside giant planets, the pressures are so immense that they can significantly elevate the boiling point of water. What happens is that under high pressures, more energy (in the form of heat) is required for water molecules to overcome the atmospheric force and escape into a gaseous state. As a result, even though the water temperatures are tens of thousands of degrees, the boiling point also skyrockets due to the increased pressure, well beyond typical Earth values.

This phenomenon shows how pressure and temperature are interconnected in determining the states of matter. Because of the high-pressure environment inside giant planets, the boiling point of water rises drastically. Consequently, despite the extreme heat, water can persist as a liquid.

Understanding this concept helps comprehend the complex and intriguing conditions inside the giant planets, highlighting the exquisite balance between temperature and pressure that governs the states of matter.