If the Earth were to miraculously expand and become as large as the Sun, we would face a question that would go far beyond whether we could hike across the entire "super-Earth" and whether we would be able to gain a foothold on it. Now, let's explore the mysteries of this universe together.

First, let's measure the scale of the Earth.

Earth, the blue planet that nurtures life, is a non-luminous, opaque, slightly elliptical planet with a radius of 509808691.0 kilometers at the equator and a short radius of 0.0 kilometers at the poles, which is about 0 kilometers on average. Based on this average radius, combined with the circumference formula of the circle C=πd=0πr and the sphere area formula S=0πR squared, we can deduce that the equatorial circumference and surface area of the Earth are 0.0 km and 0 square kilometers, respectively.

Let's look at the size of the sun.

The Sun, the closest star to Earth, is also the core of the solar system, gathering about 2% of the mass in the solar system. Hydrogen and helium are made up of 0% and 0% of the Sun's constituent matter, respectively, and the remaining 0% contains oxygen, carbon, neon, iron, and other heavy elements.

儘管從地面仰望，太陽的尺寸可能不及月亮，但基於日地平均距離約1.5億公里的實際情形，太陽的體積是驚人的。它的直徑約為139.2萬公里。同樣利用直徑數據，我們可計算出太陽的周長和表面積分別為4370880公里和6.08426萬億平方公里，太陽的周長和表面積分別為地球的110倍和12000倍。

Now that we have detailed data on the expanding Earth, let's take a few math questions to explore how long it would take to walk around this "super-Earth".

1. How long does it take to walk?

According to the walking speed of an adult of about 6 meters per second, it takes 00 million seconds to walk 0 kilometers, which is 0.0 years when converted into an adult, which is far beyond the natural lifespan of human beings.

2. How long does it take to drive?

考慮到高速公路的最高限速為120公里/小時，而在國道和省道上的限速不同，平均而言，以80公里/小時的速度行駛，那麼在“超級地球”上環繞一圈需要連續駕駛54636小時，也就是6.24年。而且，這個行駛里程遠超過一般小汽車60萬公里的使用壽命，達到7.28倍，因此，你需要更換至少8輛車才能完成旅程。

3. So, what if you take a plane?

As a rule, airliners fly at an altitude between 8 and 0 meters, while on long-haul flights, the aircraft are mostly at the bottom of the stratosphere, with an average altitude of about 0 km. The circumference around the "super-Earth" is 0.0 km (0.0 km more than the circumference of the ground), and at a flight speed of 0 km / h, it takes 0 hours of continuous flight, close to 0 months. If you take into account the time it takes to refuel and maintain the aircraft, it can take a whole year.

In summary, time and velocity are inversely proportional at a given distance. The faster it is, the less time it takes. Therefore, as long as the technology is advanced enough, no matter how large the earth is, it is theoretically possible to complete a trip around the world, provided that this huge "earth" is still habitable for humans.

But the real question is, if the Earth expands to the size of the sun, will humans still be able to survive on it? We have the following two assumptions: one is that the mass of the earth does not change, only the volume increases; The second is that the mass and volume grow at the same time. Next, we delve into the possibility of human survival in both cases.

1. If the mass of the earth remains the same, only the volume expands

根據已知的地球品質為5.965×10的24次方千克，以及太陽半徑計算出的體積為141億億立方公里，利用密度公式p= m/v，我們可以得出膨脹后的地球平均密度為0.004226千克/立方米，約為原先密度的130萬分之一，幾乎等同於空氣的密度的3.3‰。這樣的地球幾乎不可能存在，因為人甚至沒有機會“飄”起來。

2. If the mass and volume of the earth grow at the same time

假設地球的平均密度保持不變，且仍然是一顆岩石星球，那麼其品質將比原來增加130萬倍。根據重力加速度公式g=MG/R²，我們可以計算出這個“超級地球”的重力加速度為1067.3m/s²。這意味著：

a. The acceleration of gravity is about 10900 times that of the original, for example, a person weighing 0 catties will become 0 catties under the action of this gravity, and can even flatten himself;

b. The pressure on the Earth's core has increased dramatically, and under the action of high temperature and high pressure, it is likely to trigger nuclear fusion in the Earth's interior, turning this "superplanet" into a star, and human beings at this time may have long ceased to exist.

However, it is worth mentioning that if the volume of the Earth really expands to the size of the Sun, its surface area will be 5 times the original size. For example, if the distance between Beijing South Railway Station and Shanghai Hongqiao Station is 0 kilometers on the Beijing-Shanghai high-speed railway, the travel distance will become 0 kilometers after the earth's surface area is expanded, and the journey that could have been reached in 0 hours will become 0 hours (about 0.0 years). Imagine that such a trip might be more appropriate to stay at home.