Question

Suppose we were to make the following discoveries. (These are not real discoveries.) In light of your understanding of Mars, decide whether the discovery would be considered plausible or surprising. Explain clearly; because not all of these have definitive answers, your explanation is more important than your chosen answer. We find rocks on Mars showing clearly that the planet once had a global magnetic field nearly as strong as Earth's magnetic field.

Short answer

Finding such rocks is plausible, but their field strength being nearly as strong as Earth's is surprising.

Step-by-step solution

Understanding Mars' Magnetic Field

Mars does not currently possess a significant global magnetic field. However, studies on Mars' crust have shown remnant magnetization, indicating that it once had a magnetic field early in its history.

Compare with Earth's Magnetic Field

Earth has a strong and dynamic global magnetic field generated by its molten iron core. The current understanding is that Mars lost its global magnetic field about 4 billion years ago when its core solidified.

Assess the Plausibility of the Discovery

Given that Mars' early history suggests a magnetic field existed, discovering rocks with evidence of a strong global magnetic field is plausible. This aligns with theories of Mars having a once-active dynamo similar to Earth's.

Evaluate the Surprising Aspect of the Discovery

The surprising aspect would be the strength of the magnetic field being nearly as strong as Earth's. While Mars likely had a magnetic field, the theoretical models of its core suggest it was weaker than Earth's current field.

Key concepts

Planetary Science

Planetary science is the field focusing on planets, moons, and planetary systems. It explores their formation and evolution, their atmospheres, geology, and how they might sustain life.
Planetary scientists often study Mars to understand its past and present characteristics. Knowing Mars' geological history and atmospheric conditions helps scientists make comparisons with other planets, like Earth.
This is important for theories about life beyond our planet. Mars' surface shows evidence of past water flow, meteor impacts, and volcanic activity. All this shapes our understanding of the dynamic processes that govern planetary systems.

Mars History

Mars has a fascinating history that intrigues scientists. It has been a major focus in the search for past life in our solar system.
Mars formed around the same time as Earth, over 4.5 billion years ago. Initially, Mars was more Earth-like with a denser atmosphere and potentially large bodies of water.
However, as time passed, Mars lost its atmosphere, likely due to solar winds and the cooling of its core, which might have led to the shutdown of its magnetic field. This loss caused the surface water to evaporate and escape into space, leaving the barren landscape we see today.
Understanding Mars' history helps scientists learn how planetary environments can change drastically over time.

Magnetic Fields in Space

Magnetic fields play a crucial role in protecting planets and sustaining conditions for atmosphere retention and habitability.
On Earth, the magnetic field is generated by the movement of molten iron in its outer core, creating a dynamo effect.
In contrast, Mars' magnetic field evidence comes mainly from the magnetized rocks in its crust, suggesting a once-active dynamo.
Magnetic fields in space are influenced by factors like a planet's rotation speed, size, core composition, and thermal energy.
Finding rocks that indicate Mars once had a strong magnetic field hints at different dynamics in its early history than those we see today.

Planetary Geology

Planetary geology examines the structure, composition, and processes of planetary bodies.
Mars provides a detailed case study with its varied topography, including the largest volcano in the solar system, Olympus Mons, and the Valles Marineris canyon system.
Rocks on Mars, particularly those with magnetization, can reveal much about its early core activity and resulting magnetic field.
Planetary geologists study Mars' surface layers to understand both its past environments and the processes that shaped its landscape.
From impact craters to sedimentary layers, studying Mars' geology is key to piecing together its story and potential for having supported life.