On February 22, 2017, NASA reported that 7 exoplanets were found around the single star TRAPPIST-1. Three of them are in the range of distances from the star in which the planet can have liquid water, and water is a key condition for life. It is also reported that this star system is located at a distance of 40 light years from Earth.
This message caused a lot of noise in the media; some even thought that humanity was one step away from building new settlements near a new star, but this is not so. But 40 light years is a lot, it’s a LOT, it’s too many kilometers, that is, it’s a monstrously colossal distance!
From a physics course, the third escape velocity is known - this is the speed that a body must have at the surface of the Earth in order to go beyond the solar system. The value of this speed is 16.65 km/sec. Conventional orbital spacecraft take off at a speed of 7.9 km/sec and orbit the Earth. In principle, a speed of 16-20 km/sec is quite accessible to modern earthly technologies, but no more!
Humanity has not yet learned to accelerate spaceships faster than 20 km/sec.
Let's calculate how many years it will take a starship flying at a speed of 20 km/sec to travel 40 light years and reach the star TRAPPIST-1.
One light year is the distance that a beam of light travels in a vacuum, and the speed of light is approximately 300 thousand km/sec.
A human-made spaceship flies at a speed of 20 km/sec, that is, 15,000 times slower than the speed of light. Such a ship will cover 40 light years in a time equal to 40*15000=600000 years!
An Earth ship (at the current level of technology) will reach the star TRAPPIST-1 in about 600 thousand years! Homo sapiens has existed on Earth (according to scientists) for only 35-40 thousand years, but here it is as much as 600 thousand years!
In the near future, technology will not allow humans to reach the star TRAPPIST-1. Even promising engines (ion, photon, cosmic sails, etc.), which do not exist in earthly reality, are estimated to be able to accelerate the ship to a speed of 10,000 km/sec, which means that the flight time to the TRAPPIST-1 system will be reduced to 120 years . This is already a more or less acceptable time for flight using suspended animation or for several generations of immigrants, but today all these engines are fantastic.
Even the nearest stars are still too far from people, too far, not to mention the stars of our Galaxy or other galaxies.
The diameter of our Milky Way galaxy is approximately 100 thousand light years, that is, the journey from end to end for a modern Earth ship will be 1.5 billion years! Science suggests that our Earth is 4.5 billion years old, and multicellular life is approximately 2 billion years old. The distance to the closest galaxy to us - the Andromeda Nebula - 2.5 million light years from Earth - what monstrous distances!
As you can see, of all the living people, no one will ever set foot on the earth of a planet near another star.
“The search for life has begun,” says Guillem Anglada-Escudé, an astronomer at the University of London and Mary and leader of the Pale Red project team. Dot ("Pale red dot") who made the discovery.
The first excursion to a neighboring potentially habitable world could be carried out, within the framework of which it is planned to develop the concept of a fleet of spacecraft using light sails to move around the Galaxy. Another option is to send to Proxima b first. However, we are getting ahead of ourselves for now, inspired by the discovery we are rushing to the stars. But let's get back to the opening.
Today it is known that Proxima b orbits its red dwarf star (it is smaller and dimmer than the Sun) in 11 Earth days. The exoplanet is classified as rocky (has a hard surface) and is slightly larger than Earth in mass - at least 1.3 times. It is the closest exoplanet to us and possibly the closest celestial body to the Solar System on which life can exist.
Note that the cold star in the constellation Centaurus is too dim to be seen with the naked eye. It is located adjacent to the much brighter double star Alpha Centauri AB.
“, and much more remains to be discovered. But the search for the closest possible analogue of Earth and the success of these searches have become the main thing in life for all of us. Now the next stage of work lies ahead - the search for life on the planet Proxima b,” concludes Anglada-Escudé.
To some extent, the discovery of such an exoplanet can be considered the beginning of a new stage in astronomical research.
"The discovery helps us set a new goal - building a generation of tracking telescopes that will allow us to study new worlds, and perhaps one day visit them. This is exactly what we needed to take exoplanet science to the next level," says David Kipping from Columbia University in New York.
Galactic distance scales
Light year ( St. G., ly) is an extra-system unit of length equal to the distance traveled by light in one year.
More precisely, as defined by the International Astronomical Union (IAU), a light year is equal to the distance that light travels in a vacuum, unaffected by gravitational fields, in one Julian year (equal by definition to 365.25 standard days of 86,400 SI seconds, or 31,557 600 seconds). It is this definition that is recommended for use in popular science literature. In professional literature, parsecs and multiples of units (kilo- and megaparsecs) are usually used instead of light years to express large distances.
Previously (before 1984), a light year was the distance traveled by light in one tropical year, assigned to the epoch 1900.0. The new definition differs from the old one by approximately 0.002%. Since this unit of distance is not used for high-precision measurements, there is no practical difference between the old and new definitions.
Numeric values
A light year is equal to:
- 9,460,730,472,580,800 meters (approximately 9.46 petameters)
- 63,241.077 astronomical units (AU)
- 0.306601 parsecs
Related units
The following units are used quite rarely, usually only in popular publications:
- 1 light second = 299,792.458 km (exact)
- 1 light minute ≈ 18 million km
- 1 light hour ≈ 1079 million km
- 1 light day ≈ 26 billion km
- 1 light week ≈ 181 billion km
- 1 light month ≈ 790 billion km
Distance in light years
The light year is convenient for qualitatively representing distance scales in astronomy.
| Scale | Value (St. years) | Description |
|---|---|---|
| Seconds | 4 10 −8 | The average distance to is approximately 380,000 km. This means that a beam of light emitted from the surface will take about 1.3 seconds to reach the surface of the Moon. |
| minutes | 1.6·10−5 | One astronomical unit is equal to approximately 150 million kilometers. Thus, light reaches the Earth in approximately 500 seconds (8 minutes 20 seconds). |
| Watch | 0,0006 | The average distance from the Sun is approximately 5 light hours. |
| 0,0016 | The devices of the Pioneer and series flying beyond, in about 30 years since the launch, have moved to a distance of about one hundred astronomical units from the Sun, and their response time to requests from the Earth is approximately 14 hours. | |
| Year | 1,6 | The inner edge of the hypothetical is located at 50,000 a. e. from the Sun, and the outer one - 100,000 a. e. It will take about a year and a half for light to travel the distance from the Sun to the outer edge of the cloud. |
| 2,0 | The maximum radius of the region of gravitational influence of the Sun (“Hill Spheres”) is approximately 125,000 AU. e. | |
| 4,2 | The closest one to us (not counting the Sun), Proxima Centauri, is located at a distance of 4.2 light years. of the year. | |
| Millennium | 26 000 | The center of our Galaxy is approximately 26,000 light-years from the Sun. |
| 100 000 | The diameter of our disk is 100,000 light years. | |
| Millions of years | 2.5 10 6 | The closest M31 to us, the famous one, is 2.5 million light years away from us. |
| 3.14 10 6 | (M33) is located 3.14 million light years away and is the most distant stationary object visible to the naked eye. | |
| 5.8 10 7 | The closest one, the Virgo cluster, is 58 million light years away from us. | |
| Tens of millions of light years | The characteristic size of galaxy clusters by diameter. | |
| 1.5 10 8 - 2.5 10 8 | The “Great Attractor” gravitational anomaly is located at a distance of 150-250 million light years from us. | |
| Billions of years | 1.2 10 9 | The Great Wall of Sloan is one of the largest formations in the world, its dimensions are about 350 Mpc. It will take about a billion years for light to travel from end to end. |
| 1.4 10 10 | The size of the causally connected region of the Universe. It is calculated from the age of the Universe and the maximum speed of information transmission - the speed of light. | |
| 4.57 10 10 | The accompanying distance from the Earth to the edge of the observable Universe in any direction; accompanying radius of the observable Universe (within the framework of the standard cosmological model Lambda-CDM). |
It is this definition that is recommended for use in popular science literature. In professional literature, parsecs and multiples of units (kilo- and megaparsecs) are usually used instead of light years to express large distances.
Previously (before 1984), a light year was the distance traveled by light in one tropical year, assigned to the epoch 1900.0. The new definition differs from the old one by approximately 0.002%. Since this unit of distance is not used for high-precision measurements, there is no practical difference between the old and new definitions.
Numeric values
A light year is equal to:
- 9,460,730,472,580,800 meters (approximately 9.5 petameters)
Related units
The following units are used quite rarely, usually only in popular publications:
- 1 light second = 299,792.458 km (exact)
- 1 light minute ≈ 18 million km
- 1 light hour ≈ 1079 million km
- 1 light day ≈ 26 billion km
- 1 light week ≈ 181 billion km
- 1 light month ≈ 790 billion km
Distance in light years
The light year is convenient for qualitatively representing distance scales in astronomy.
| Scale | Value (St. years) | Description |
|---|---|---|
| Seconds | 4 10 −8 | The average distance to the Moon is approximately 380,000 km. This means that a beam of light emitted from the surface of the Earth will take about 1.3 seconds to reach the surface of the Moon. |
| minutes | 1.6·10−5 | One astronomical unit is equal to approximately 150 million kilometers. Thus, light travels from the Sun to Earth in approximately 500 seconds (8 minutes 20 seconds). |
| Watch | 0,0006 | The average distance from the Sun to Pluto is approximately 5 light hours. |
| 0,0016 | The Pioneer and Voyager series devices flying beyond the solar system, in about 30 years since launch, have moved to a distance of about one hundred astronomical units from the Sun, and their response time to requests from Earth is approximately 14 hours. | |
| Year | 1,6 | The inner edge of the hypothetical Oort cloud is located at 50,000 AU. e. from the Sun, and the outer one - 100,000 a. e. It will take about a year and a half for light to travel the distance from the Sun to the outer edge of the cloud. |
| 2,0 | The maximum radius of the region of gravitational influence of the Sun (“Hill Spheres”) is approximately 125,000 AU. e. | |
| 4,22 | The closest star to us (not counting the Sun), Proxima Centauri, is located at a distance of 4.22 light years. of the year . | |
| Millennium | 26 000 | The center of our Galaxy is approximately 26,000 light-years from the Sun. |
| 100 000 | The diameter of the disk of our Galaxy is 100,000 light years. | |
| Millions of years | 2.5 10 6 | The closest spiral galaxy to us, M31, the famous Andromeda Galaxy, is 2.5 million light years away. |
| 3.14 10 6 | The Triangulum Galaxy (M33) is located 3.14 million light-years away and is the most distant stationary object visible to the naked eye. | |
| 5.9 10 7 | The closest cluster of galaxies, the Virgo cluster, is 59 million light-years away. | |
| 1.5 10 8 - 2.5 10 8 | The “Great Attractor” gravitational anomaly is located at a distance of 150-250 million light years from us. | |
| Billions of years | 1.2 10 9 | The Great Wall of Sloan is one of the largest formations in the Universe, its dimensions are about 350 Mpc. It will take about a billion years for light to travel from end to end. |
| 1.4 10 10 | The size of the causally connected region of the Universe. It is calculated from the age of the Universe and the maximum speed of information transmission - the speed of light. | |
| 4.57 10 10 | The accompanying distance from the Earth to the edge of the observable Universe in any direction; accompanying radius of the observable Universe (within the framework of the standard cosmological model Lambda-CDM). |
Galactic distance scales
- An astronomical unit with good accuracy is equal to 500 light seconds, that is, light reaches the Earth from the Sun in about 500 seconds.
see also
Links
- International Organization for Standardization. 9.2 Measurement units
Notes
Wikimedia Foundation. 2010.
See what “Light Year” is in other dictionaries:
An extra-system unit of length used in astronomy; 1 S.g. is equal to the distance traveled by light in 1 year. 1 S. g. = 0.3068 parsec = 9.4605 1015 m. Physical encyclopedic dictionary. M.: Soviet Encyclopedia. Editor-in-Chief A. M. Prokhorov... ... Physical encyclopedia
LIGHT YEAR, a unit of astronomical distance equal to the distance that light travels in outer space or in a VACUUM in one tropical year. One light year is equal to 9.46071012 km... Scientific and technical encyclopedic dictionary
LIGHT YEAR, a unit of length used in astronomy: the path traveled by light in 1 year, i.e. 9.466?1012 km. The distance to the nearest star (Proxima Centauri) is approximately 4.3 light years. The most distant stars in the Galaxy are located on... ... Modern encyclopedia
Unit of interstellar distances; the path that light travels in a year, i.e. 9.46? 1012 km... Big Encyclopedic Dictionary
Light year- LIGHT YEAR, a unit of length used in astronomy: the path traveled by light in 1 year, i.e. 9.466´1012 km. The distance to the nearest star (Proxima Centauri) is approximately 4.3 light years. The most distant stars in the Galaxy are located on... ... Illustrated Encyclopedic Dictionary
An extra-system unit of length used in astronomy. 1 light year is the distance that light travels in 1 year. 1 light year is equal to 9.4605E+12 km = 0.307 pc... Astronomical Dictionary
Unit of interstellar distances; the path that light travels in a year, that is, 9.46·1012 km. * * * LIGHT YEAR LIGHT YEAR, a unit of interstellar distances; the path that light travels in a year, i.e. 9.46×1012 km... encyclopedic Dictionary
Light year- a unit of distance equal to the path traveled by light in one year. A light year is equal to 0.3 parsecs... Concepts of modern natural science. Glossary of basic terms