Question

Which object's gravity holds the planets in their orbits? A. Gaspra C. Mercury B. Earth D. the Sun

Short answer

The Sun's gravity holds the planets in their orbits.

Step-by-step solution

Understand the Concept of Orbit

An orbit is the path that an object takes as it moves around another object in space. In our solar system, planets move in orbits around a central object due to gravitational attraction.

Identify the Source of Gravity in the Solar System

The strongest gravitational force in the solar system comes from the Sun. It is much more massive than any other object in the solar system, and this gravitational pull keeps the planets, including Earth and Mercury, in their orbits.

Eliminate the Incorrect Options

Gaspra is an asteroid and does not have the mass to hold planets in orbit. Earth and Mercury, while they have gravity, do not exert enough gravitational force to keep the whole solar system in orbit. Only the Sun is massive enough.

Verify the Correct Answer

Considering the information, the Sun's gravity is what holds the planets in their orbits. This matches with choice D, confirming that the Sun is the correct answer.

Key concepts

Planetary Orbits

In the solar system, each planet moves in a distinct path around the Sun called an orbit. This path is typically elliptical in shape, which means it looks like an elongated circle. The reason planets follow these specific paths is due to the balance between gravity and the momentum of the planets. As a planet moves forward in space, the gravitational pull from the Sun bends its path, creating an orbit.

Key facts about planetary orbits include:

• Orbits are primarily shaped by the gravitational pull of the Sun.
• Each planet's orbit varies in size and shape depending on its distance from the Sun and its speed.
• Gravitational interactions with other celestial bodies can also influence orbits slightly.

Understanding orbits helps us predict the position of planets in the solar system, which is crucial for navigation and space exploration.

Gravitational Force

Gravitational force is a fundamental interaction that causes attraction between masses. In the context of the solar system, gravity is what keeps the planets tethered to the Sun. This force is determined by two primary factors: the mass of the objects and the distance between them.

Important insights on gravitational force:

• The formula to calculate gravitational force is given by Newton's Law of Universal Gravitation: \[ F = G \frac{{m_1 \cdot m_2}}{{r^2}} \]where \( F \) is the force between the masses, \( G \) is the gravitational constant, \( m_1 \) and \( m_2 \) are the masses, and \( r \) is the distance between the centers of the two masses.
• The larger the mass, the stronger the gravitational pull.
• The closer two objects are, the stronger the gravitational attraction between them.

Gravitational force is essential for maintaining the stability of orbits in the solar system.

Solar System Education

Understanding the solar system is a fascinating journey into how celestial bodies interact and coexist. Education about the solar system provides insights into various scientific principles such as gravity, planetary motion, and cosmic interactions.

Focus areas for solar system education:

• The role of the Sun as the central and most massive body, exerting gravitational force that governs the motion of other bodies.
• Exploration of planets, moons, asteroids, and comets that each have unique characteristics and contributions to solar system dynamics.
• The historical and modern tools used for observation, including telescopes and space probes.

By deepening knowledge of the solar system, students can appreciate the complexities and beauty of our cosmic neighborhood, fostering a sense of curiosity and exploration.