The distances between stars are so great that measuring them in kilometers or miles is an exercise with endless zeros. The usual measurement system is used to designate distances in one system. For example, they say that the minimum distance from Earth to Mars is 55.76 million kilometers. With stars, everything is more complicated, and here the concepts of light year and parsec are usually used.

Astronomical unit- a unit of measurement adopted in astronomy for objects of the Solar System and the objects of the Universe closest to it. An astronomical unit is equal to 149,598,100 km (+- ~750 km), which is approximately equal to the average distance of the Earth from the Sun. Modern observations have recorded a gradual increase in value by 15 cm annually, which is explained by the possible loss of mass by the Sun, the consequences of the solar wind.

Light year- the distance that light travels in one year, in meters it is 9,460,730,472,580,800. In fact, the light of the stars that we see on a cloudless night traveled to our planet for many centuries, and some of them no longer exist at all.

Parsec, also known as “arcsecond parallax,” is the distance from which the average radius of the Earth’s orbit (perpendicular to the line of sight) is visible at an angle of one arcsecond. Quite simply, a parsec = 3.26 light years.

It is interesting that in popular science and fantasy literature it is customary to use the concept of a light year, and parsecs are usually used only in professional works and research.

(Galaxy UDFj-39546284 is the farthest galaxy from Earth (13.3 billion light years from Earth), in the image taken by the Hubble telescope it looks like a red dot)

The closest star to us is Alpha Centauri, which is located 4.37 light years from Earth. But the most distant galaxy (as of December 2012) is as much as 13.3 billion light years from Earth! It turns out that when the sun of this very galaxy (known under the symbol UDFj-39546284) goes out, humanity will not know about it soon.

A light year is the distance that light travels in one year. The International Astronomical Union has given its explanation of the light year - this is the distance that light travels in a vacuum, without the participation of gravity, in a Julian year. The Julian year is equal to 365 days. It is this decoding that is used in scientific literature.

If we take professional literature, then the distance is calculated in parsecs or kilo- and megaparsecs.

There are specific numbers that determine the distance of light hours, minutes, days, etc.

• A light year is equal to 9,460,800,000,000 km,
• month- 788,333 million km.,
• a week- 197,083 million km.,
• day- 26,277 million km,
• hour- 1,094 million km.,
• minute- about 18 million km.,
• second- about 300 thousand km.

This is interesting! From the Earth to the Moon, light travels on average in 1.25 seconds, while its beam reaches the Sun in just over 8 minutes.

Interesting fact about the nature of the universe

The star Betelgeuse in the constellation Orion should explode in the foreseeable future (in fact, within a few centuries).

Betelgeuse is located at a distance of 495 to 640 light years from us.
If it explodes right now, then the inhabitants of the Earth will see this explosion only in 500-600 years.

And if you see an explosion today, then remember that in fact the explosion occurred around the time of Ivan the Terrible...

Earth year

An earthly year is the distance traveled by the earth in one year. If we take into account all the calculations, then one light year is equal to 63242 Earth years. This figure applies specifically to planet Earth; for others, such as Mars or Jupiter, they will be completely different. A light year measures the distance from one celestial object to another. The numbers for light years and earth years are so different, although they mean distance.

Quick answer: not at all.

We are often asked very interesting questions, the answers to which are very non-standard. You see one of these questions in the title. And really, how many Earth years are there in one light year? You may be disappointed, but the correct answer is not at all. How so?

The thing is that a light year is not a measure of time, but a measure of distance. To be more precise, 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), according to definition of the International Astronomical Union.

Now let's try to calculate the distance of a light year. To do this, let’s take the mark of 300 thousand kilometers per second (this is exactly the speed of light) and multiply by 31.56 million seconds (so many seconds in a year) and get a huge figure - 9,460,800,000,000 km (or 9,460,000 million kilometers). This fantastic figure means a distance that is equal to a light year.

• 1 light month ~ 788,333 million km

• 1 light week ~ 197,083 million km

• 1 light day ~ 26,277 million km

• 1 light hour ~ 1,094 million km

• 1 light minute ~ approximately 18 million km

• 1 light second ~ 300 thousand km

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.