165 years
How long it would take to get to Neptune from Earth would depend on the path chosen and on where Neptune and Earth were in their orbits when the mission was launched. For example, the Voyager 2 spacecraft was launched on Aug 20, 1977 and it reached Neptune on Aug 24, 1989.  To determine how long it will take to reach Mars, we must first know the distance between the two planets. Mars is the fourth planet from the sun, and the second closest to Earth (Venus is the closest). But the distance between the two planets is constantly changing as they travel around the sun. Here is a list of how long it took several historical missions to reach the red planet. Their launch dates are included for perspective. 1  Mariner 4, the first spacecraft to go to Mars (1964 flyby): 228 days. 2  Mariner 6 (1969 flyby): 155 days. 3  Mariner 7 (1969 flyby): 128 days The journey from Earth to Mars takes about 300 days. Every two years Mars is at its closest point, only 55 million km from Earth, and it's the ideal time to send a spacecraft. Travel time depends on the positions of the planets and how much fuel you're willing to burn. When you're trying to get to Mars, just like in a car, spending more fuel means a shorter travel time. The first spacecraft to make this journey was NASA's Mariner 4, launched on November 28, 1964 and arrived 228 days later. Mariner 9, the first spacecraft to successfully go into orbit around Mars launched on May 30, 1971, and arrived November 13, 1971 for a duration of 167 days. This is the same pattern that has held up for more almost 50 years of Mars exploration: approximately 150-300 days. When you consider the fact that Mars is only 55 million km away, and the spacecraft are travelling in excess of 20,000 km/hour, you would expect the spacecraft to make the journey in about 115 days, but it takes much longer. Every two years or so, Mars and Earth reach their closest point, called “opposition”, when Mars can be as close as 55,000,000 km from Earth. And every two years, space agencies take advantage of this orbital alignment to send spacecraft to the Red Planet. When you consider the fact that Mars is only 55 million km away, and the spacecraft are travelling in excess of 20,000 km/hour, you would expect the spacecraft to make the journey in about 115 days, but it takes much longer. Light itself takes 4.6 hours to travel from the Earth to Pluto. If you wanted to send a signal to Pluto, it would take 4.6 hours for your transmission to reach Pluto, and then an additional 4.6 hours for their message to return to us. Let’s talk spacecraft. When New Horizons blasted off from Earth, it was going 58,000 km/h. For a more detailed discussion, see the. How long does it take? It takes the Earth one year to orbit the Sun and it takes Mars about 1.9 years (say 2 years for easy calculation) to orbit the Sun. The elliptical orbit which carries you from Earth to Mars is longer than Earth's orbit, but shorter than Mars' orbit. All in all, your trip to Mars would take about 21 months: 9 months to get there, 3 months there, and 9 months to get back. With our current rocket technology, there is no way around this. The long duration of trip has several implications How long does it take for all nine planets to orbit around the sun? Mercury. . . 88 earth days Venus. . . 225 days Earth. . . 365 days Mars. . . 685 days Jupiter. . . 12 earth years Saturn. . . 29 years Uranus. . . 84 years … Neptune. . . 165 years Pluto. . . Expelled from the lofty fraternity and demoted to dwarf planet.
http://coolcosmos.ipac.caltech.edu/ask/143-How-long-does-it-take-to-get-to-Neptune-from-Earth- http://www.space.com/24701-how-long-does-it-take-to-get-to-mars.html http://www.youtube.com/watch?v=MpOJ6fQ0roI http://www.universetoday.com/14841/how-long-does-it-take-to-get-to-mars/ http://www.universetoday.com/14841/how-long-does-it-take-to-get-to-mars/ http://www.universetoday.com/119264/how-long-does-it-take-to-get-to-pluto/ http://image.gsfc.nasa.gov/poetry/venus/q2811.html http://www.answers.com/Q/Whow_long_does_it_take_all_planets_to_orbit_round_the_sun
how long would it take to go to planet nine