### Define light year and explain its value in astronomy?

A light-year is the distance light travels in a year - equivalent to almos 10 million million (or 1013) kilometers. In popular astronomy, distances to stars or galaxies are often stated in light-years; although astronomers often prefer another measure, the parsec, equivalent to about 3.26 light-years. A light-year is the distance light travels in a year - equivalent to almos 10 million million (or 1013) kilometers. In popular astronomy, distances to stars or galaxies are…

### How many light-years is the Sun from Earth?

A year is a measure of time. A light-year is a measure of distance - the distance light travels in a year. The sun is about 150 million kilometres from the Earth - 96 million miles. The speed of light in a vacuum is roughly 300,000,000 metres per second, so the light from the Sun takes about 8.3 minutes to reach the Earth.

### What is the size in square miles of the Universe?

First, you would measure the diameter of the Universe in miles, or its volume in cubic miles; but what would you want to measure in square miles? Second, the size of the Universe is not currently known. The observable Universe has a radius of about 46 billion light-years. Convert that to kilometers or miles if you like. One light-year is about 10 million million kilometers. But the entire Universe is probably much, much bigger. First…

### Why do astronemers use light-years to measure distances in space?

Distances in space are so far apart, that we need a really long unit of measurement to express the distance. A star that's 4 1/2 light years away is so far away from the Earth, that to express it in miles would take a very big number indeed. Most objects in the universe are so far apart that even a light-year is small compared to the vast distances.

### Why is an object 15 million light years away like looking at an object 15 million years ago?

Because you might have seen it in a telescope years ago idk Another Answer A light year is a measure of distance. If an object is 15 million light years away, the light you are looking at in this moment was produced 15 million years ago. If a star that far away went supernova at this moment, we wouldn't know it for another 15 million years. The light we see on the surface of our…

### How far away is Venus from Earth in light years?

Venus is much less than a light-year away. Venus varies in its distance from Earth between about 26 million and 160 million miles, as they orbit the sun separately. This works out to a range of 0.000004 to 0.000027 light years. Within the solar system it would be better to measure distances in light minutes than light years.

### How far is 430 light years?

Each light-year is the distance light travels in a year - almost 10 million million (1013) kilometers, or 1016 meters. Each light-year is the distance light travels in a year - almost 10 million million (1013) kilometers, or 1016 meters. Each light-year is the distance light travels in a year - almost 10 million million (1013) kilometers, or 1016 meters. Each light-year is the distance light travels in a year - almost 10 million million…

### How are an astronomical unit and a light year similar in terms of what they measure?

They are very similar because they are both units of spatial measurement (they measure distances). They are alike because they are both used to measure very long distances in space. 1 Astronomical Unit = distance from Earth to Sun (approx. 93 million miles) 1 Light Year = the distance light rays (photons) travel in one Earth year (approx. 6 trillion miles)

### Why can't astronomers measure the parrallax of a star that is a million light year's away?

A million light-years is about 300,000 parsecs; that would mean a parallax of 1/300,000 arc-seconds. Such a small angle can't be measured yet. A million light-years is about 300,000 parsecs; that would mean a parallax of 1/300,000 arc-seconds. Such a small angle can't be measured yet. A million light-years is about 300,000 parsecs; that would mean a parallax of 1/300,000 arc-seconds. Such a small angle can't be measured yet. A million light-years is about 300,000…

### A mega-parsec is equivalent to?

Mega means million. A megaparsec is a million parsecs. Each parsec is about 3.26 light-years. Mega means million. A megaparsec is a million parsecs. Each parsec is about 3.26 light-years. Mega means million. A megaparsec is a million parsecs. Each parsec is about 3.26 light-years. Mega means million. A megaparsec is a million parsecs. Each parsec is about 3.26 light-years.