托福閱讀天文類背景材料：火星上的四季都比地球要寒冷

Mars Overview

Mars, the fourth planet from the Sun, has a radius approximately half that of Earth, with a volume accounting for 15% and a mass representing 11% of Earth's. Its surface area is comparable to that of Earth's landmass, but its density is significantly lower than that of the other three terrestrial planets: Earth, Venus, and Mercury. In terms of radius, mass, and surface gravity, Mars lies between Earth and the Moon: its radius is about twice that of the Moon and half that of Earth; its mass is nine times that of the Moon and one-ninth that of Earth, while its surface gravity is 2.5 times that of the Moon and about 0.4 times that of Earth.

Seasons on Mars

Known as the "Red Planet" due to its iron oxide-rich surface, Mars is often associated with the Roman god of war, Mars, and is referred to as "Yinghuo" in Chinese, meaning "the fire star." The tilt of Mars's rotational axis is similar to that of Earth, which suggests that it experiences seasons akin to those on Earth. This was first proposed by the astronomer William Herschel in 1781 when he observed the movement of markings across the Martian surface as it rotated.

Length of a Martian Year

A year on Earth lasts approximately 365.2422 days. However, the duration of a year varies across celestial bodies in the solar system. Among the terrestrial planets (Mercury, Venus, and Mars), Mars has the longest year, taking about 687 Earth days to complete one orbit around the Sun. Given that the axial tilt of Mars is nearly identical to that of Earth, one might expect the seasonal changes to be similar. Yet, each season on Mars lasts about twice as long as those on Earth, and because Mars is farther from the Sun, its seasons are generally colder than their Earth counterparts.

Seasonal Differences

Moreover, Mars's elliptical orbit is more elongated than that of Earth, leading to more pronounced seasonal differences between its northern and southern hemispheres. Consequently, the variations in season lengths on Mars are also greater than those on Earth. While seasonal length differences on Earth do not exceed 5%, spring in the northern hemisphere of Mars can be approximately one-third longer than autumn.

托福閱讀天文類背景材料：火星上的四季都比地球要寒冷,。通過以上分析，我們可以更深入地理解火星的季節(jié)變化及其與地球的不同之處,，這對于托?？忌谔煳膶W相關(guān)主題的閱讀理解中具有重要意義。

As a TOEFL test-taker, understanding various topics can significantly enhance your reading and writing skills. One intriguing subject is the characteristics of seasons on Mars. This article delves into the unique features of Martian seasons, providing insights that may help you in your TOEFL preparation. ??

1. Introduction to Martian Seasons

Mars has a rotational period similar to Earth, taking about 24.6 hours to complete one rotation. However, its axial tilt is approximately 25 degrees, which is quite similar to Earth's 23.5 degrees. This tilt results in distinct seasons on Mars, just like on our planet. ??

2. Duration of Seasons

One of the most notable differences between Earth and Mars is the length of the seasons. A Martian year lasts about 687 Earth days, which means each season is nearly twice as long as those on Earth. For instance, summer in the northern hemisphere can last for about 7 months, while winter can extend for around 5 months. This extended duration affects the planet's climate and weather patterns. ??

3. Seasonal Changes in the Northern Hemisphere

During the northern summer, temperatures can rise significantly, reaching up to 20 degrees Celsius (68 degrees Fahrenheit) near the equator. This warmth leads to the sublimation of carbon dioxide ice caps, creating vast dust storms that can envelop the planet. As fall approaches, temperatures drop, and the polar ice caps begin to reform. By winter, temperatures can plummet to -125 degrees Celsius (-195 degrees Fahrenheit) at the poles. ??

4. Southern Hemisphere Seasons

In contrast, the southern hemisphere experiences its summer when the northern hemisphere is in winter. The southern summer is characterized by even more extreme conditions, with temperatures potentially exceeding 30 degrees Celsius (86 degrees Fahrenheit). The southern polar ice cap also undergoes significant changes, expanding and contracting throughout the year. ???

5. Dust Storms and Seasonal Impact

One of the most fascinating aspects of Martian seasons is the occurrence of dust storms. These storms can cover large areas of the planet and are most common during the spring and summer months. They can last for weeks or even months, affecting visibility and temperature across the surface. Understanding these storms is crucial for future exploration missions. ???

6. Implications for Future Exploration

For students preparing for the TOEFL, knowing about Martian seasons can be beneficial, especially if you encounter related topics in reading or listening sections. The knowledge of how seasons affect the Martian environment can also provide context for discussions on potential human colonization and the challenges it may present. ??

7. Conclusion

In summary, the study of Martian seasons reveals a complex interplay of climatic conditions that differ significantly from those on Earth. With longer seasons and extreme temperature variations, Mars presents unique challenges and opportunities for exploration. As you prepare for your TOEFL exam, consider how this knowledge might enrich your understanding of planetary science and enhance your academic vocabulary. ??

Understanding Astronomy in TOEFL Reading

As a TOEFL candidate, mastering various topics, including astronomy, is essential for achieving a high score. Astronomy, the study of celestial bodies and the universe, often appears in TOEFL reading passages. Here are some tips to help you navigate these texts effectively! ??

Key Vocabulary to Know

Familiarizing yourself with astronomy-related vocabulary can significantly enhance your comprehension. Here are a few important terms:

• Celestial Bodies: Objects in space, such as stars, planets, and moons.
• Orbit: The path an object takes as it revolves around another object in space.
• Galaxy: A massive system of stars, gas, dust, and dark matter, bound together by gravity.
• Black Hole: A region in space where the gravitational pull is so strong that nothing, not even light, can escape from it.
• Supernova: An astronomical event that occurs during the last stages of a massive star's life, resulting in a tremendous explosion.

Reading Strategies

When approaching astronomy passages in the TOEFL reading section, consider these strategies:

• Skim the Passage: Quickly read through the passage to get a general idea of the topic. Look for keywords related to astronomy. ??
• Identify Main Ideas: Focus on the main arguments or points made in each paragraph. This will help you answer questions more effectively.
• Take Notes: Jot down important facts or concepts as you read. This can aid in retaining information and answering detail-oriented questions later.

Sample Passage

Here’s a brief example of what an astronomy-related passage might look like:

The Universe and Its Expansion

The universe is constantly expanding, a phenomenon first observed by Edwin Hubble in the 1920s. This expansion is measured by the redshift of distant galaxies, indicating they are moving away from us. As galaxies recede, the fabric of space itself stretches, leading to a greater distance over time. Understanding this expansion helps scientists learn about the universe's origins and its ultimate fate.

Practice Questions

After reading a passage, you may encounter questions like these:

• What evidence supports the claim that the universe is expanding?
• How did Edwin Hubble contribute to our understanding of the universe?

Listening Practice

In addition to reading, listening to discussions about astronomy can also be beneficial. Here’s a sample listening prompt:

Listening Text:

“Today, we will discuss the lifecycle of stars. Stars are born in nebulae, which are clouds of gas and dust. Over millions of years, gravity pulls the material together, forming a star. Once a star has formed, it spends most of its life in a stable phase, fusing hydrogen into helium. Eventually, stars exhaust their fuel, leading to various endings, such as becoming a red giant or exploding as a supernova.”

Preparation Tips

To prepare for astronomy-related content on the TOEFL, consider the following:

• Read Astronomy Articles: Websites like NASA or popular science magazines can provide valuable insights and vocabulary.
• Watch Documentaries: Visual learning can reinforce concepts and make them easier to remember.
• Practice with Sample Tests: Familiarize yourself with the format of TOEFL questions and practice under timed conditions.

Final Thoughts

By incorporating these strategies and resources into your study routine, you will be better equipped to tackle astronomy passages on the TOEFL reading section. Good luck with your preparation! ??