Universe Today

How far away is Uranus from the Sun? The average distance from Uranus to the Sun is 2.87 billion km, or 1.78 billion miles.

Keep in mind that this is just an average. Uranus follows an elliptical path around the Sun, so sometimes it's closer than 2.87 billion km, and other times it's further away. At the closest point of its orbit, called perihelion, Uranus measures 2.74 billion km. And then at the furthest point of its orbit, known as aphelion, Uranus measures 3.00 billion km from the Sun.

You can also measure the distance from Uranus to the Sun in astronomical units. 1 astronomical unit is the average distance from the Earth to the Sun; approximately 150 million km. Uranus' average distance from the Sun is 19.2 AU. Its shortest distance from the Sun is 18.4 AU, and its greatest distance is 20.1 AU.

The distance to Uranus is so great that only one spacecraft has ever made the journey. Launched in 1977, Voyager 2 flew past Uranus in 1986, passing within 107,000 km of the cloudtops on Uranus. Voyager 2 provided the first closeup photographs of Uranus and discovered ten new moons.

We have written many articles about Uranus for Universe Today. Here's an article with some interesting facts about Uranus, and here's an article about a dark spot seen in the clouds of Uranus.

If you'd like more information on Uranus, check out NASA's World Book on Uranus. And here's a link to NASA's Solar System Exploration Guide to Uranus.

We've also recorded an entire episode of Astronomy Cast all about Uranus. Listen here, Episode 62: Uranus.

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How far away is Pluto from the Sun? Pluto's average distance from the Sun is 5.9 billion km or 3.7 billion miles.

But Pluto actually follows an elliptical orbit around the Sun. Sometimes it's much closer to the Sun, and other times it's further away. At its closest point, Pluto measures only 4.4 billion km from the Sun. This is close enough that a thin layer of frost evaporates from its surface, becoming a thin atmosphere around the planet. And then as it continues its journey around the Sun, Pluto gets colder again and this atmosphere refreezes onto the planet. It continues to travel out to a distance of 7.4 billion km from the Sun.

Astronomers use another method of measuring distances in the Solar System called the astronomical unit. 1 astronomical unit or AU is the average distance from the Earth to the Sun; approximately 150 million km. So we can use this to describe Pluto's distance from the Sun. At its closest point, Pluto measures 29.7 AU. And then at its furthest point, Pluto is 49.3 AU.

We have written many articles about Pluto for Universe Today. Here's an article about why Pluto isn't a planet any more, and here are some pictures of Pluto.

If you'd like more info on Pluto, check out NASA's World Book on Pluto, and here's NASA's Solar System Exploration Guide to Pluto.

We've also recorded several episodes of Astronomy Cast about Pluto. Listen here, Episode 64: Pluto and the Icy Outer Solar System.

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How far away is Mars? The minimum distance from Earth to Mars is 55.7 million km, or 34.6 million miles.

But think about the orbit of Earth and Mars around the Sun. This closest point happens when Earth and Mars are lined up on the same side of the Sun (Sun – Earth – Mars). When Mars is at its closest point, astronomers call this opposition. This is when Mars can be only 55.7 million km from Earth. The average Mars opposition distance is 78 million km.

And then when Mars and Earth are on opposite sides of the Sun (Earth – Sun – Mars), Mars can be 401.3 million km from Earth.

A Mars opposition happens every 26 months, when the two planets are lined up together. This is a useful launch windows for sending spacecraft from Earth to Mars. NASA usually launches a spacecraft during each one of these launch windows. The last mission to go to Mars was the Mars Phoenix Lander, and the next one to launch will be the Mars Curiosity Rover in 2011.

We have written many articles about Mars for Universe Today. Here's an article about the gravity on Mars and here's an article about a simulated Mars mission.

If you'd like more info on Mars, check out NASA's Mars Exploration mission page, and here's a link to NASA's World Book on Mars.

We have also recorded several episodes of Astronomy Cast about Mars. Here's a link to Episode 52: Mars.

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How far away is Mars from the Sun? The average distance from Mars to the Sun is approximately 228 million km, or 142 million miles.

But as I said, this number is an average. Mars travels in an elliptical orbit around the Sun. Sometimes it gets closer and other times it's more distant. At its closest point, Mars is only 207 million km from the Sun. Astronomers call this point in a planet's orbit perihelion. And then at its most distant point, called aphelion, Mars reaches a distance of 249 million km from the Sun.

Mars actually has one of the most elliptical, or eccentric, orbits in the Solar System. Astronomers calculate its eccentricity as 0.093.

Astronomers use a standard measurement tool called an astronomical unit to calculate distances in the Solar System. Mars' average distance from the Sun is 1.52 AU, its perihelion is 1.38 AU, and its aphelion is 1.67 AU.

We have written many articles about Mars for Universe Today. Here's an article about how trips to Mars might be shortened down to 39 days with new technology, and here is some new information about why Mars is red.

If you'd like more information on Mars, check out NASA's homepage for Mars Exploration. And check out NASA's World Book on Mars.

We've also recorded many episodes of Astronomy Cast about Mars. Here's a good one, Episode 52: Mars.

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How far away is the Sun from Earth? The average distance from the Earth to the Sun is 149,597,887 km, or 92,955,817 miles.

This number is an average though. The Earth actually follows an elliptical path around the Sun. There are times when it's closer, and times when it's more distant. The closest point of the Earth's orbit around the Sun is called perihelion, when the Earth is approximately 147 million km away from the Sun. And then the most distant point of our planet's orbit is known as aphelion, where the Earth measures 152 million km from the Sun.

The average distance from the Earth to the Sun is known as an astronomical unit, which measures approximately 150 million km. You can measure the distance to other planets in the Solar System in astronomical units (or AU). Mars is an average distance of 1.5 AU from the Sun, and Neptune is 30.1 AU from the Sun.

We have written many articles about the Sun for Universe Today. Here's an article about the layers of the Sun, and here's some information on the temperature of the Sun.

If you'd like more info on the Sun, check out NASA's World Book on the Sun, and here's a link to the homepage of NASA's SOHO mission, which is currently studying the Sun.

We have also recorded several episodes of Astronomy Cast about the Sun. Here's a good one, Episode 30: The Sun, Spots and All.

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How far away is the Moon? The Moon is an average distance of 384,399 km, or 238,854 miles from the Earth.

That's an average, though. The Moon travels in an elliptical orbit around the Earth. Sometimes it's closer and sometimes it's more distant. From here on Earth, the size of the Moon can vary by more than 15% in size from when it's at its closest to when it's at the most distant point. When the Moon is at the closest, called perihelion, it's only 363,104 km from Earth. And then at its most distant point, called aphelion, the Moon is 405,696 km from Earth.

The brightest full Moons occur when the Moon is at the closest. A large, bright full Moon can be 30% brighter than when it's at its the most far away.

Astronomers know the exact distance to the Moon because there are small retroreflectors sitting on the Moon which bounce laser light. They were put there by the Apollo astronauts during their missions for just this purpose. Astronomers fire a laser pulse at the Moon and time how long it takes to make a return trip from Earth to the Moon and back. They can then calculate how far away the Moon is.

We've written many articles about the Moon for Universe Today. Here's an article about how LCROSS discovered buckets of water on the Moon, and here's an article about how long it takes to get to the Moon.

If you'd like more info on the Moon, check out NASA's World Book on the Moon, and here's a link to the Lunar and Planetary Science page on the Moon.

We have recorded several episodes of Astronomy Cast about the Moon. Here's a good one, Episode 113: The Moon, Part 1.

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The Sun is the key to life on Earth, and yet it's incredibly far away. How far away is the Sun? On average, the Sun is approximately 150 million kilometers or 93 million miles away from the Earth.

This number is an average, though, because the Earth follows an elliptical path around the Sun. Sometimes it's closer and other times it's more distant from the Sun. At the closest point of the Earth's orbit, called perihelion, the Sun is 147 million km away from Earth. And then at the most distant point of the Earth's orbit, known as aphelion, the Sun is 152 million km away from Earth.

Astronomers actually use the average distance from the Sun to the Earth as a standard measuring tool for calculating distances in the Solar System. 1 astronomical unit, or AU, is the average distance from the Earth to the Sun; approximately 150 million km. So, Mars is 1.5 AU from the Sun, and Pluto is 39.5 AU from the Sun.

We've written many articles about the Sun for Universe Today. Here's an article about the Sun's lithium mystery, and here's an article about how big the Sun is.

If you'd like more info on the Sun, check out NASA's World Book on the Sun, and here's the homepage to NASA's SOHO mission page, where new images of the Sun are constantly released.

We've also recorded several episodes of Astronomy Cast about the Sun. Listen here, Episode 30: The Sun, Spots and All.

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Question: how far is it from the Earth to the Moon? The average distance from the Earth to the Moon is 384,399 km or 238,854 miles.

This is an average number, though. The Moon actually takes an elliptical path around the Earth. Sometimes it's closer, getting as close as 363,104 km. And it can also be further, getting as far as 405,696 km.

When the Moon can look 15% larger when it's at the closest point of its orbit. And every few years the closest Moon happens at the same time that the Moon is full. When this happens, it can be 30% brighter when we see a full Moon when it's at the furthest point of its orbit.

Scientists actually know the distance to the Moon within a few centimeters. When the astronauts of the Apollo missions were on the Moon, they placed small reflective mirrors on the surface. Scientists on Earth can shoot a laser beam and calculate how long it takes to bounce off these reflectors and return to Earth. By knowing the speed of light, they can calculate the distance light traveled to get to the Moon and back.

We have written many articles about the Moon for Universe Today. Here's an article about looking at the Moon in a telescope, and here's an article about the Moon landing hoax.

If you'd like more info on the Moon, check out this article that explains the retroflectors that scientists use to determine the distance to the Moon.

We've also recorded many episodes of Astronomy Cast about the Moon. Here's a good one, Episode 113: The Moon, Part 1.

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If you were wondering how far is Mars from the Earth, I'm happy to report that the distance is actually pretty close (in cosmic terms). The minimum distance from the Earth to Mars is 55.7 million km, or 34.6 million miles.

When Mars is at its closest point to Earth in orbit, it's known as "opposition". A Mars opposition happens every 26 months, and during this period, Mars is one of the brightest objects in the sky; clearly visible with the unaided eye as a bright red star. In this configuration, when it's Sun – Earth – Mars, the Red Planet is only 55.7 million km away. And then, 13 months later, Earth and Mars are on opposite sides of the Sun (Earth – Sun – Mars); this is known as conjunction, and Mars is located 401.3 million km from Earth.

Rocket scientists take advantage of the close approach to Mars every 26 months to launch spacecraft towards the Red Planet. During each window, NASA usually launches a new mission to Mars. At the time of this writing, the next window will be November, 2011, when NASA is set to launch the Curiosity Rover.

We have written many articles about Mars for Universe Today. Here's an article about how new technology could bring the time for a trip to Mars down to only 39 days, and here are some amazing Martian dunes.

If you'd like more info on Mars, I suggest you start with NASA's Mars Exploration page. And then check out the NASA World Book on Mars.

We have also recorded several episodes of Astronomy Cast all about Mars. Here's a good one, Episode 52: Mars.

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How far is Venus from Earth? Venus gets pretty close, actually. The minimum distance from Venus to Earth is 38.2 million km, or 23.7 million miles.

This is the minimum number, though, when Venus and Earth are at their closest point. When they're at their closest point, Venus is said to be in inferior conjunction (Sun – Venus – Earth). This is when the two planets are only 38.2 million km apart. And then when Earth and Venus are on opposite sides of the (Venus – Sun – Earth), Venus is in superior conjunction – the distance is 261 million km.

Because Venus gets so close to Earth, and it reflects back so much of the light that it receives from the Sun, Venus is the third brightest object in the sky (after the Moon and the Sun). But when Venus is close, we're actually seeing most of the planet in shadow. The bright side is facing towards the Sun. We see Venus as a crescent, similar to the Moon. But even then it's still brighter than anything else but the Moon and the Sun.

We have written many articles about Venus for Universe Today. Here's an article about how Venus might have once had oceans and continents, and here's an article about lightning storms seen on Venus.

If you'd like more info on Venus, check out NASA's World Book on Venus, and the NASA/JPL Solar System Exploration Guide to Venus.

We have also recorded an episode of Astronomy Cast all about Venus. Listen here, Episode 50: Venus.

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Here's a question: how far is the Sun from Earth? Well, the average distance from the Sun to Earth is 149,597,887.5 km, or 92955817.7 miles.

This is an average distance, though. The Earth actually follows an elliptical orbit around the Sun. At times it gets closer to the Sun, called perihelion, when it's only 147 million km. And then at the furthest point of its orbit, called aphelion, the Sun is 152 million km from Earth.

In fact, astronomers use this distance between Sun and Earth as a standard measuring tool for calculating distances in the Solar System. 1 astronomical unit, or AU, is the average distance between the Earth and the Sun; about 150 million km. You can express distances in the Solar System in astronomical units. For example, the distance from the Sun to Mars is 1.523 AU. And the distance from the Sun to Pluto is 39.5 AU.

We have written many articles about the Sun for Universe Today. Here's an article about how far all the planets are from the Sun, and here's an article about the mass of the Sun.

If you'd like more info on the Sun, check out NASA's World Book on the Sun, or the homepage for the SOHO spacecraft, which is constantly observing the Sun.

We have also recorded several episodes of Astronomy Cast about the Sun. Listen to Episode 30: The Sun, Spots and All.

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How far is Mars from Earth? The minimum distance from Earth to Mars is 55.7 million km, or 34.6 million miles.

This number is a minimum, though. Keep in mind that Earth and Mars are both orbiting around the Sun. They're at their closest when they're lined up Sun – Earth – Mars. At this closest point, the two planets are only 55.7 million km apart. But they're at their most distant point when they're aligned Earth – Sun – Mars. Then they're 401.3 million km apart.

With such a big variation in distance, Mars can be dim or bright in the sky depending on how far it is. And this closest point is achieved every 26 months or so, which astronomers call opposition. Just before a Mars opposition is the best time to launch spacecraft to make the long journey to Mars. It allows them to use the least amount of fuel, reaching the Red Planet in just a few months.

We have written many articles about Mars for Universe Today. Here's an article about a strange rock found on Mars. And here's an article about how spacecraft might be able to make the trip to Mars in only 39 days in the future.

If you'd like more info on Mars, check out NASA's Mars Exploration page. You can get more info from NASA's World Book on Mars.

We have also recorded an entire episode of Astronomy Cast all about Mars. Listen here, Episode 52: Mars.

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Are you wondering how far is the Moon from Earth? Well, the exact number is an average of 384,399 km, or 238,854 miles.

This number is an average because the Moon takes an elliptical orbit around the Earth. Sometimes it's closer than this average number, and other times it's more distant. At its closest point, called perihelion, the Moon measures 363,104 km from the Earth. And then at the most distant point of its orbit, known as aphelion, the Moon is 405,696 km from Earth. This is a big difference: 42,592 km.

Because of this huge different in difference, the size and brightness of the Moon can change dramatically when the full Moon matches up with a close Moon. It can be 15% larger and 30% brighter than an average Moon.

You might be surprised to know that astronomers have actually measured how far the moon is from Earth to within a few centimeters. They're able to do this because the Apollo astronauts left small reflective mirrors on the surface of the Moon during their last mission. Astronomers on Earth fire a laser pulse at the Moon and measure how long it takes to hit the Moon, bounce off the reflectors and return to Earth. By knowing the speed of light, and timing the return journey of the light pulse, they're able to calculate the distance to the Moon with incredible accuracy.

We've written many articles about the Moon for Universe Today. Here's an article about the discovery of water on the Moon, and here's an article about an eclipse seen from the Moon.

If you'd like more information on the Moon, NASA has some great resources. Check out NASA's World Book on the Moon. And here's NASA's Lunar and Planetary Science page on the Moon.

We have also recorded many episode of Astronomy Cast about the Moon. Listen here, Episode 113: The Moon, Part 1.

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The minimum distance from Earth to Uranus is 2.582 billion km, or 1.604 billion miles.

Keep in mind that both Earth and Uranus are orbiting the Sun, so the distance between both planets is always changing. When they're on the same side of the Sun (Sun – Earth – Uranus), their distance is only 2.582 billion km. But when they're on opposite sides of the Sun (Earth – Sun – Uranus), the distance is 3.157 billion km.

This is such a great distance that only one spacecraft, Voyager 2, has ever made the journey. It arrived at Uranus in 1986, passing within 107,000 km of Uranus and discovering 10 new moons.

We've written many articles about Uranus for Universe Today. Here's an article with some interesting facts about Uranus, and here's an article about how Hubble saw a rare transit on Uranus.

And if you'd like more information on Uranus, check out NASA's World Book on Uranus, or the NASA/JPL Solar System Exploration Guide to Uranus.

We've also recorded an entire episode of Astronomy Cast just about Uranus. Listen here, Episode 62: Uranus.

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The minimum distance from Earth to Neptune is 4.305 billion km, or 2.672 billion miles.

Now this is a minimum because the distance to Neptune from Earth is constantly changing as the two planets orbit the Sun. At their closest point, the planets are lined up on the same side of the Sun (Sun – Earth – Neptune), and they're 4.305 billion km apart. And then at their most distant point, the planets are on opposite sides of the Sun (Earth – Sun – Neptune), and they're 4.687 billion km apart.

This is such a great distance that only one spacecraft has ever made the journey from Earth to Neptune. That was NASA's Voyager spacecraft, which arrived at Neptune in 1989, passing within 4,800 km of Neptune. Voyager 2 made new observations of Neptune's rings and discovered 6 new moons around the planet.

We've written many articles about Neptune for Universe Today. Here's an article about how Neptune might have captured its moon Triton, and the gravity on Neptune.

If you'd like more info on Neptune, check out NASA's World Book on Neptune. And here's a link to NASA's Solar System Exploration Guide.

We've also recorded an entire episode of Astronomy Cast just about Neptune. Listen here, Episode 63: Neptune.

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