Worksheet for the "Birth of the Solar System" video, guiding students to fill in key terms related to the formation of the solar system.

Problem Explanation:

The worksheet titled "Birth of the Solar System" is designed to help students understand the formation of the solar system by filling in blanks based on a video. The questions cover key concepts such as the collapse of a nebula, the formation of the Sun and planets, and the processes involved in planetary accretion.

Solution with Explanations:

#### 1. Our own nebula began its collapse ________ years ago.
- Answer: 4.6 billion
- Explanation: The solar system formed approximately 4.6 billion years ago when a giant molecular cloud (nebula) collapsed under its own gravity.

#### 2. It is likely that the nebula had been slowly spinning in space ever since its creation. But as its material collapsed, it began to spin ________.
- Answer: much faster
- Explanation: As the nebula collapsed, conservation of angular momentum caused it to spin faster. This is similar to how a figure skater spins faster when they pull their arms inward.

#### 3. A dense clump of matter formed in the center, called a ________.
- Answer: protostar
- Explanation: The central region of the collapsing nebula became very dense and hot, forming a protostar, which is the precursor to a star.

#### 4. When the clump reached 18 million degrees Fahrenheit, ________ kicked in.
- Answer: nuclear fusion
- Explanation: At extremely high temperatures, hydrogen nuclei fuse together to form helium, releasing energy. This process is called nuclear fusion and marks the birth of the Sun.

#### 5. Four and a half billion years ago, our ________ was born.
- Answer: star
- Explanation: The Sun, our central star, was born around 4.5 billion years ago when nuclear fusion began in the protostar.

#### 6. The collapse of our giant cloud of dust may have been triggered by the blast from a nearby ________.
- Answer: supernova
- Explanation: The shockwave from a nearby supernova explosion could have compressed the nebula, triggering its gravitational collapse.

#### 7. When compressed enough, ________ would start to have an effect and the cloud would begin to ________.
- Answer: gravity; collapse
- Explanation: Gravity becomes the dominant force as the cloud compresses, causing it to collapse further due to self-gravity.

#### 8. Within the cloud, swirling about the infant Sun, the ________ are beginning to take shape.
- Answer: planets
- Explanation: As the nebula collapses, material begins to form into planets orbiting the young Sun.

#### 9. Tiny particles of dust begin to clump together in a process known as ________.
- Answer: accretion
- Explanation: Accretion is the process by which small particles stick together to form larger bodies, eventually leading to the formation of planets.

#### 10. Once the clumps reach the size of ________, they exert a significant gravitational force, which causes the process to accelerate.
- Answer: mountains
- Explanation: When the clumps grow large enough (about the size of mountains), their gravitational pull becomes strong enough to attract more material, accelerating the growth process.

#### 11. In about 1 million years, the clumps can grow into larger ________, or pieces of planets, and can keep on growing into full-sized ________.
- Answer: planetesimals; planets
- Explanation: Planetesimals are intermediate-sized objects that form during the early stages of planet formation. These can continue to grow into full-sized planets through further accretion.

#### 12. When it is strong enough, gravity will re-sculpt any body into a ________. This is why all the planets are roughly spherical.
- Answer: sphere
- Explanation: Strong gravitational forces cause objects to become spherical because gravity pulls equally from all directions, resulting in a nearly perfect sphere.

#### 13. At first, all the matter around our young star is so hot that it is a ________ form.
- Answer: gaseous
- Explanation: Initially, the temperature was too high for solid or liquid forms, so all matter existed in a gaseous state.

#### 14. In the inner solar system, closest to the Sun, it stays hot: way too hot for ________ or ________ to condense; but ________ particles can condense here. The metallic planet that formed in this region is ________.
- Answer: gases; ices; metallic; mercury
- Explanation: Close to the Sun, temperatures were too high for gases or ices to condense, but metallic particles could solidify. Mercury, being the closest planet to the Sun, is primarily composed of these metallic materials.

#### 15. Further out, the temperature drops about 1000°F, so more ________ particles can condense, allowing the rockier terrestrial planets ________, ________, and ________ to form in this region.
- Answer: rocky; Venus; Earth; Mars
- Explanation: As you move farther from the Sun, temperatures drop, allowing rocky materials to condense. This region gave rise to the terrestrial planets: Venus, Earth, and Mars.

#### 16. All of the gas compounds condense much further out, but before this zone is the ________.
- Answer: asteroid belt
- Explanation: Beyond the terrestrial planets lies the asteroid belt, where many small rocky and metallic objects remain undisturbed.

Final Answer:

\boxed{
\begin{aligned}
&1. \text{4.6 billion} \\
&2. \text{much faster} \\
&3. \text{protostar} \\
&4. \text{nuclear fusion} \\
&5. \text{star} \\
&6. \text{supernova} \\
&7. \text{gravity}; \text{collapse} \\
&8. \text{planets} \\
&9. \text{accretion} \\
&10. \text{mountains} \\
&11. \text{planetesimals}; \text{planets} \\
&12. \text{sphere} \\
&13. \text{gaseous} \\
&14. \text{gases}; \text{ices}; \text{metallic}; \text{mercury} \\
&15. \text{rocky}; \text{Venus}; \text{Earth}; \text{Mars} \\
&16. \text{asteroid belt}
\end{aligned}
}