>>Physics: Gravity on other planets
Before the invention of the telescope, only seven planets were known: Mercury, Venus, Mars, Jupiter, Saturn, Earth and the Moon. Their number suited many. Therefore, when Galileo’s book “The Starry Messenger” was published in 1610, in which he reported that with the help of his “spotting scope” he was able to discover four more celestial bodies, “not seen by anyone from the beginning of the world to the present day” (satellites Jupiter), this caused a sensation. Galileo's supporters rejoiced at the new discoveries, while his opponents declared an irreconcilable war on the scientist.
A year later, the book “Reflections on Astronomy, Optics and Physics” was published in Venice, in which the author argued that Galileo was mistaken and the number of planets must necessarily be seven, since, firstly, the Old Testament mentions a seven-branched candlestick (which means seven planets), secondly, there are only seven holes in the head, thirdly, there are only seven metals and, fourthly, “the satellites are not visible to the naked eye, and therefore cannot influence the Earth, therefore, they are not are needed, and therefore they do not exist.”
However, such arguments could not stop the development of science, and now we know for sure that the satellites of Jupiter exist and the number of planets is not at all seven. Nine revolve around the sun major planets(Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, of which only the first two do not have satellites) and over three thousand small planets called asteroids.
Satellites orbit around their planets under the influence of their gravitational field. The force of gravity on the surface of each planet can be found using the formula F t= mg, Where g=GM/R2- acceleration of free fall on the planet. Substituting mass into the last formula M and radius R different planets, you can calculate what the acceleration of free fall is equal to g on each of them. The results of these calculations (in the form of the ratio of the acceleration of gravity on a given planet to the acceleration of gravity on the Earth's surface) are given in Table 7.
Table 7
From this table it can be seen that the greatest acceleration of gravity and, therefore, the greatest force of gravity is on Jupiter. It is the largest planet in the solar system; its radius is 11 times and its mass is 318 times greater than that of the Earth. The attraction is weakest on distant Pluto. This planet is smaller than the Moon: its radius is only 1150 km, and its mass is 500 times less than that of the Earth!
The small planets of the solar system have even less mass. 98% of these celestial bodies orbit the Sun between the orbits of Mars and Jupiter, forming the so-called asteroid belt. The first and largest asteroid, Ceres, was discovered in 1801. Its radius is about 500 km, and its mass is approximately 1.2 1021 kg (i.e., 5000 times less than that of the Earth). It is easy to calculate that the acceleration of gravity on Ceres is approximately 32 times less than on Earth! The weight of any body turns out to be the same number of times less. Therefore, an astronaut who found himself on Ceres could lift a load weighing 1.5 tons (Fig. 110).
However, no one has yet been to Ceres. But people have already been to the Moon. This first happened in the summer of 1969, when the Apollo 11 spacecraft delivered three American astronauts to our natural satellite: N. Armstrong, E. Aldrin and M. Collins. “Of course,” Armstrong later said, “in conditions of lunar gravity, you want to jump up... The highest jump height was two meters - Aldrin jumped to the third step of the lunar cabin stairs. The falls had no unpleasant consequences. The speed is so low that there is no reason to fear any injury.”
The acceleration of free fall on the Moon is 6 times less than on Earth. Therefore, when jumping upward, a person rises there to a height 6 times greater than on Earth. To jump 2 meters on the Moon, as Aldrin did, requires the same force as on Earth when jumping 33 cm.
The first astronauts were on the Moon for 21 hours and 36 minutes. On July 21, they launched from the Moon, and on July 24, Apollo 11 splashed down in the Pacific Ocean. People left the Moon, but five medals with images of five dead astronauts remained on it. These are Yu. A. Gagarin, V. M. Komarov, V. Grissom, E. White and R. Chaffee.
???
1. List all the major planets that make up the Solar System.
2. What are the names of the largest and the smallest of them?
3. How many times does the weight of a person on Jupiter exceed the weight of the same person on Earth?
4. How many times is the gravity on Mars less than on Earth?
5. What do you know about Ceres?
6. Why did the astronauts on the Moon walk more like jumping than normal walking?
If you have corrections or suggestions for this lesson,
> > > Gravity on Mars
Which gravity on Mars compared to the Earth: description of indicators for the planets of the solar system with photos, impact on the human body, calculation of gravity.
Earth and Mars are similar in many ways. They are virtually convergent in surface area, have polar caps, axial tilt, and seasonal variability. In addition, both show that they have survived climate change.
But they are also different. And one of the most important factors is gravity. Believe me, if you are going to colonize an alien world, then this moment will play an important role.
Comparison of gravity on Mars and Earth
We know that Earth's conditions helped life form, so we use them as a guide when searching for alien life. Atmospheric pressure on Mars is 7.5 millibars versus 1000 on Earth. The average surface temperature drops to -63°C, and ours is 14°C. The photo shows the structure of Mars.
If the length of the Martian day is almost identical to the Earth's (24 hours and 37 minutes), then the year covers as many as 687 days. Martian gravity is 62% lower than on Earth, that is, 100 kg there turns into 38 kg.
This difference is affected by mass, radius and density. Despite the similarity in surface area, Mars covers only half the Earth's diameter, 15% of the volume and 11% of the massiveness. What about the gravity of Mars?
Calculating Mars' gravity
To determine Martian gravity, the researchers used Newton's theory: gravity is proportional to mass. We are colliding with a spherical body, so gravity will be inversely proportional to the square of the radius. Below is a gravity map of Mars.
The proportions are expressed by the formula g = m/r 2, where g is surface gravity (multiples of Earth = 9.8 m/s²), m is mass (multiple of Earth = 5.976 10 24 kg), and r is radius (multiple of Earth = 6371 km) .
The Martian mass is 6.4171 x 10 23 kg, which is 0.107 times greater than ours. The average radius is 3389.5 km = 0.532 Earth's. Mathematically: 0.107/0.532² = 0.376.
We do not know what will happen to a person if he is immersed in such conditions for a long period of time. But studies of the effects of microgravity show loss of muscle mass, bone density, damage to organs and decreased vision.
Before we go to a planet, we must study its gravity in detail, otherwise the colony is doomed to death.
There are already projects that deal with this issue. So Mars-1 is developing programs to improve muscles. A stay on the ISS longer than 4-6 months shows a loss of muscle mass by 15%.
But the Martian one will take much more time for the flight itself, where the ship is attacked by cosmic rays, and staying on the planet, where there is also no protective magnetic layer. Crew missions of the 2030s It's getting closer, so we must make addressing these issues a priority. Now you know what gravity looks like on Mars.
It is well known that the Earth has the shape of a sphere, flattened at the poles. Therefore, the weight of the same body (determined by the force of gravity) in different places on the planet is not the same. For example, an adult, moving from high latitudes to the equator, will “lose weight” about 0.5 kg. What is the force of gravity on other planets in the solar system?
Sir Newton's theory
One of the founding fathers of classical mechanics, the great English mathematician, physicist and astronomer Isaac Newton, while studying the movement of the Moon around our planet, formulated the Law of Universal Gravitation in 1666. According to the scientist, it is the force of gravity that underlies the movement of all bodies in space and on Earth, be it planets revolving around stars or an apple falling from branches. According to the Law, the force of attraction between two material bodies is proportional to the product of their masses and inversely proportional to the square of the distance between the bodies.
If we talk about the force of gravity on Earth and other planets or astronomical objects, then from the above it becomes clear that it is proportional to the mass of the object and inversely proportional to the square of its radius. Before we go on a space journey, let's consider the gravitational forces on our planet.
Weight and mass
A few words about physical terms. The theory of classical mechanics states that gravity arises due to the interaction of a body with a cosmic object. The force with which this body acts on the support or suspension is called the weight of the body. The unit of measurement for this quantity is newton (N). In physics, weight is denoted, like force, by the letter F and is calculated using the formula F = mg, where coefficient g is the acceleration of gravity (near the surface of our planet g = 9.81 m/s 2).
Mass is understood as a fundamental physical parameter that determines the amount of matter contained in a body and its inert properties. Traditionally measured in kilograms. Body mass is constant in every corner of our planet and even the solar system.
If the Earth had a strictly spherical shape, the weight of a certain object at different geographical latitudes of the earth's surface at sea level would be unchanged. But our planet has the shape of an ellipsoid of rotation, and the polar radius is 22 km shorter than the equatorial one. Therefore, according to the Law of Universal Gravitation, the weight of a body at the pole will be 1/190 greater than at the equator.
On the Moon and the Sun
Based on the formula, the force of gravity on other planets and astronomical bodies can be easily calculated, knowing their mass and radius. By the way, the methods and methods for determining these quantities are based on the same Newton’s Law of Universal Gravitation and Kepler’s 3rd Law.
The mass of the cosmic body closest to us - the Moon - is 81 times, and the radius is 3.7 times less than the corresponding terrestrial parameters. Thus, the weight of any body on the only natural satellite of our planet will be six times less than on Earth, while the acceleration of gravity will have a value of 1.6 m/s 2.
On the surface of our star (near the equator) this parameter has a value of 274 m/s 2 - the maximum in the Solar System. Here the gravity is 28 times greater than on Earth. For example, a person weighing 80 kg has a weight on Earth of about 800 N, on the Moon - 130 N, and on the Sun - more than 22,000 N.
In 2006, astronomers around the world agreed to believe that the Solar System includes eight planets (Pluto was classified as a dwarf planet). Conventionally, they are divided into two categories:
- Terrestrial group (from Mercury to Mars).
- Giants (from Jupiter to Neptune).
Determination of gravity on other planets is carried out according to the same principle as for the Moon.
At the center of the solar system
Space objects belonging to the first group are located inside the orbit of the asteroid belt. These planets are characterized by the following structure:
- The central region is a hot and heavy core consisting of iron and nickel.
- The mantle, most of which consists of ultramafic igneous rocks.
- Crust consisting of silicates (exception: Mercury). Due to the rarefied atmosphere, its upper layer is heavily destroyed by meteorites).
Some astronomical parameters and gravity on other planets are briefly reflected in the table.
Based on the data in the table, we can determine that the force of gravity on the surface of Mercury and Mars is 2.6 times less than on Earth, and on Venus the weight of an astronaut will be only 1/10th less than on Earth.
Giants and dwarfs
The giant planets, or outer planets, are located beyond the orbit of the Main Asteroid Belt. At the base of each of these bodies is a small rock core, covered with a huge gaseous mass, consisting mainly of ammonia, methane and hydrogen. Giants have short periods of revolution around their axis (from 9 to 17 hours), and when determining gravitational parameters it is necessary to take into account the action of centrifugal forces.
The body weight on Jupiter and Neptune will be greater than on Earth, but on other planets the gravity force is slightly less than Earth’s. These objects do not have a solid or liquid surface, so calculations are carried out for the boundary of the upper cloud layer (see table).
| Orbital radius (million km) | Radius (thousand km) | Weight (kg) | Acceleration of freedom drop g (m/s 2) | Astronaut weight (N) | |
| Jupiter | 778 | 71 | 1.9×10 27 | 23,95 | 1677 |
| Saturn | 1429 | 60 | 5.7×10 26 | 10,44 | 730 |
| Uranus | 2871 | 26 | 8.7×10 25 | 8,86 | 620 |
| Neptune | 4504 | 25 | 1.0×10 26 | 11,09 | 776 |
(Note: data on Saturn in many sources (digital and printed) is very contradictory).
In conclusion, a few interesting facts that give a clear idea of what gravity is on other planets. The only celestial body visited by representatives of humanity is the Moon. According to the recollections of American astronaut Neil Armstrong, a heavy protective suit did not prevent him and his colleagues from easily jumping to a height of up to two meters - from the surface to the third step of the lunar module ladder. On our planet, the same effort only resulted in a jump of 30-35 cm.
There are several other dwarf planets orbiting the Sun. The mass of one of the largest - Ceres - is 7.5 thousand times less, and the radius is two dozen times less than that of Earth. The force of gravity on it is so weak that an astronaut could easily move a load weighing about 2 tons, and having pushed off from the surface of the “dwarf”, he would simply fly into outer space.
Jupiter
The mass of this gas giant exceeds the mass of our old Earth by more than 300 times, moreover, its mass is twice as large as all the planets of the solar system combined! Just imagine what a huge mass this is. And all this mass consists mainly of Hydrogen and Helium. These two gases form the basis of the upper layers. Scientists suggest that the planet's core still consists of heavier elements. But no one knows for sure. There are at least 63 moons orbiting Jupiter. The four largest of them were first discovered in 1610 by Galileo Galilei. They were later named “Galilean” in his honor. Isn't it interesting, but it gets better! About 15 years ago, a theory took root in astrophysics that this giant has an interesting property. It turns out that this planet, that is, Jupiter, has, one might say, a vital function for our Earth. Due to its enormous mass and rapid rotation, this giant has an increased gravitational force. For comparison, we can take our gravity, to which we are all accustomed. On earth the coefficient of gravity is 10 N/kg. On Jupiter, the same coefficient is 24 N/kg. Roughly speaking, if you suddenly found yourself on Jupiter, you would weigh about 2.5 times more. Based on the data presented above, it is logical to assume that all space objects flying close to Jupiter will change their trajectory, up to a complete change in course and fall onto the surface of the gas giant.
jupiter planet power space
In support of this theory, one can cite the fact that one of Jupiter’s satellites, Ganymede, has a diameter greater than the diameter of the planet of the solar system, Mercury. Due to the fact that Ganymede is also affected by the gravity of our star, that is, the Sun, it does not fall on Jupiter, but does not break away from it. Ganymede moves around Jupiter in a circumplanetary orbit created by two forces: the gravity of Jupiter and the gravity of the Sun. This giant has such power, let alone asteroids whose mass is much less than the mass of Ganymede. If we consider the diagram of the construction of planets, it turns out that our Earth is closer to the Sun. Next comes Mars, followed by Jupiter. And behind Jupiter there is a very interesting planet and it is called, as you probably already guessed, Saturn. We can talk a lot about Saturn, but today we are interested in only one point. Saturn is surrounded by a belt of meteorites. So, following the same logic, we can assume that from time to time some meteorites may fall out of this belt. This is where Jupiter comes into play. We have already said that Jupiter has a very strong gravitational field. Therefore, a meteorite, breaking out of the belt and passing in close proximity to Jupiter, obeying the laws of the universe, under the influence of Jupiter’s gravity, inevitably changes its course. And, in the end, it flies not towards the Sun, but towards the surface of Jupiter. If it were not for Jupiter, then it is quite likely that the trajectory of the meteorite could well intersect with the trajectory of our Earth. And then who knows what disasters these collisions could bring. It should also be noted that Saturn is not the only supplier of meteorites. But all meteorites whose trajectory coincides with the trajectory of Jupiter will no longer pose a threat to planets located closer to the sun, including our earth. And besides meteorites, there are other celestial bodies that can pose a threat in the event of a collision. You probably guessed what I mean - these are comets. Comets enter our Solar System mainly from the Orth cloud, which is the outer region within which comets orbit in very large numbers. So, some astrophysicists suggest that Jupiter is capable of “throwing away” cosmic bodies arriving in our system from the Oort cloud.
Recently, a group of scientists created a number of computer models of our solar system. In these models, our system developed in different construction options. In some, Jupiter was removed from the solar system altogether. In other cases, its mass was reduced. So, studies have shown that if Jupiter did not exist at all, then the probability of a collision between our earth and a cosmic body would be reduced by 30%. But here it should be said that the influence on the asteroid belt, one might say the largest belt located between Jupiter and Mars, has not been fully studied. So the result may not be accurate. But a study in which the mass of Jupiter was reduced by four times relative to its real mass led to amazing results. As a result, it was revealed that the probability of asteroid bombardment of the earth was 500% higher than in the case where the planet Jupiter was absent altogether. Based on all of the above, it can be assumed that the gas giant is still significant for protecting our Earth from attacks from space.
Before the invention of the telescope, only seven planets were known: Mercury, Venus, Mars, Jupiter, Saturn, Earth and the Moon. Their number suited many. Therefore, when Galileo’s book “The Starry Messenger” was published in 1610, in which he reported that with the help of his “spotting scope” he was able to discover four more celestial bodies, “not seen by anyone from the beginning of the world to the present day” (satellites Jupiter), this caused a sensation. Galileo's supporters rejoiced at the new discoveries, while his opponents declared an irreconcilable war on the scientist.
A year later, the book “Reflections on Astronomy, Optics and Physics” was published in Venice, in which the author argued that Galileo was mistaken and the number of planets must necessarily be seven, since, firstly, the Old Testament mentions a seven-branched candlestick (which means seven planets), secondly, there are only seven holes in the head, thirdly, there are only seven metals and, fourthly, “the satellites are not visible to the naked eye, and therefore cannot influence the Earth, therefore, they are not are needed, and therefore they do not exist.”
However, such arguments could not stop the development of science, and now we know for sure that the satellites of Jupiter exist and the number of planets is not at all seven. Nine large planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, of which only the first two do not have satellites) and over three thousand small planets called asteroids revolve around the Sun.
Satellites orbit around their planets under the influence of their gravitational field. The force of gravity on the surface of each planet can be found using the formula F T = mg, where g = GM/R 2 is the acceleration of gravity on the planet. Substituting the mass M and radius R of different planets into the last formula, we can calculate what the gravitational acceleration g is equal to on each of them. The results of these calculations (in the form of the ratio of the acceleration of gravity on a given planet to the acceleration of gravity on the Earth's surface) are given in Table 7.
From this table it can be seen that the greatest acceleration of gravity and, therefore, the greatest force of gravity is on Jupiter. It is the largest planet in the solar system; its radius is 11 times and its mass is 318 times greater than that of the Earth. The attraction is weakest on distant Pluto. This planet is smaller than the Moon: its radius is only 1150 km, and its mass is 500 times less than that of the Earth!
The small planets of the solar system have even less mass. 98% of these celestial bodies orbit the Sun between the orbits of Mars and Jupiter, forming the so-called asteroid belt. The first and largest asteroid, Ceres, was discovered in 1801. Its radius is about 500 km, and its mass is approximately 1.2 * 10 21 kg (i.e., 5000 times less than that of the Earth). It is easy to calculate that the acceleration of gravity on Ceres is approximately 32 times less than on Earth! The weight of any body turns out to be the same number of times less. Therefore, an astronaut who found himself on Ceres could lift a load weighing 1.5 tons (Fig. 110). 
However, no one has yet been to Ceres. But people have already been to the Moon. This first happened in the summer of 1969, when the Apollo 11 spacecraft delivered three American astronauts to our natural satellite: N. Armstrong, E. Aldrin and M. Collins. “Of course,” Armstrong later said, “in conditions of lunar gravity, you want to jump up... The highest jump height was two meters - Aldrin jumped to the third step of the lunar cabin stairs. The falls had no unpleasant consequences. The speed is so low that there is no reason to fear any injury.”
The acceleration of free fall on the Moon is 6 times less than on Earth. Therefore, when jumping upward, a person rises there to a height 6 times greater than on Earth. To jump 2 meters on the Moon, as Aldrin did, requires the same force as on Earth when jumping 33 cm.
The first astronauts were on the Moon for 21 hours and 36 minutes. On July 21, they launched from the Moon, and on July 24, Apollo 11 splashed down in the Pacific Ocean. People left the Moon, but five medals with images of five dead astronauts remained on it. These are Yu. A. Gagarin, V. M. Komarov, V. Grissom, E. White and R Chaffee.
1. List all the major planets that make up the Solar System. 2. What are the names of the largest and the smallest of them? 3. How many times does the weight of a person on Jupiter exceed the weight of the same person on Earth? 4. How many times is the gravity on Mars less than on Earth? 5. What do you know about Ceres? 6. Why did the astronauts on the Moon walk more like jumping than normal walking?