How many light-years away is Neptune from Earth?

nirmalya_b

Actually, Neptune is around four light hours from the Earth (243 light minutes), not even a light year. http://wiki.answers.com/Q/How_far_from_Earth_is_Neptune_in_light-years http://library.thinkquest.org/03oct/01944/light.htm#lig May 28 09, 8:24 PM

Watchkeeper

Both planets are in motion, so the distance between them varies considerably. There are two extremes: Firstly, Earth is furthest from the Sun (aphelion, 152,097,701 km) and Neptune is in opposition (directly opposite the Sun in the sky so that the Earth is exactly between the Sun and Neptune) and nearest to the Sun (perihelion, 4,452,940,833 km). The separation is then 4,452,940,833 km - 152,097,701 km or 4,300,843,132 km. Since 1 light year is 9,460,730,472,580.8 km, Neptune will be 0.0004546 of a light year away. This is the closest possible. Secondly, Earth is at aphelion and Neptune is at aphelion but in conjunction - diametrically opposite the Earth on the other side of the Sun. In this case the separation will be 4,553,946,490 km + 152,097,701 km or 4,706,044,191 km. This is 0.0004974 of a light year, the furthest possible. These simplified calculations do not take account of the 1.768° orbital inclination of Neptune. http://en.wikipedia.org/wiki/Neptune http://en.wikipedia.org/wiki/Earth%27s_orbit http://en.wikipedia.org/wiki/Light_year May 29 09, 7:37 AM