|
The New Horizons probe, now halfway to Pluto, will get sharper images of Pluto when it is six months away from a close flyby in 2015.
This is the most detailed view to date of the entire surface of the dwarf planet Pluto, as constructed from multiple Hubble Space Telescope photographs taken from 2002 to 2003. |
POOR little Pluto. Once considered one of the nine major planets in the solar system, it was demoted to dwarf planet status by astronomers in 2006. Dwarf planet or not, it has not yet been visited by spacecraft, but that will change in July 2015 when NASA's New Horizons mission will study mysterious Pluto and its moons.
Speaking of Pluto's natural satellites, did you know that Pluto now has five known moons? The fifth moon orbiting Pluto recently was discovered by the Hubble Space Telescope in July.
The moon is estimated to be only 6 to 15 miles in diameter, and while its size may not be significant, its discovery clearly demonstrates that the Pluto system is more complex than previously imagined.
Because of Pluto's crowded environment, astronomers are continuing to keep a sharp eye on it for the next few years to ensure the New Horizons spacecraft has a clear path when it enters Pluto's neighborhood. Launched in January 2006, New Horizons has been blazing a steady path toward Pluto. Ensuring that the spacecraft does not encounter any unknown obstacles is paramount when New Horizons conducts the first-ever reconnaissance of the Pluto system.
Pluto is so distant from the sun that very little is known about it. Its diameter is 1,485 miles, so it is smaller than our own moon. Pluto's size and mass are not large enough for it to clear its orbit of other objects, and this is why it was reclassified as a dwarf planet in 2006. While the dwarf planet designation may apply to Pluto for the foreseeable future, its growing family of moons is invoking surprise in the astronomical community. It also raises the question of whether the planetary definition will change again based on the number of moons orbiting a planet.
Obviously, we've only begun to learn about this dark and distant part of the solar system where Pluto resides. Pluto will hold more surprises for us, which will be revealed when New Horizons visits it in 2015. Follow the New Horizons mission on the Internet: http://pluto.jhuapl.edu/
SEPTEMBER SKIES
Mars and Saturn are visible very low in the southwestern sky after sunset this month. Look for the moon to be between the planetary pair during the evening of the 18th and near Mars during the evening of the 19th.
Jupiter and Venus rule the morning skies this month. The moon will pose near Jupiter during the morning of the 8th and near Venus during the morning of the 12th.
The autumnal equinox, also known as the first day of fall, arrives on September 22.
David Abbou of Stafford County is a volunteer for the NASA/JPL Solar System Ambassadors Program and is a member of the Rappahannock Astronomy Club. Contact him at
Email: dabbou@comcast.net.
