Tonight – September 25, 2015 – don’t expect to see the planet Neptune. Even on the darkest of moonless nights, you need an optical aid to see Neptune, the eighth planet outward from the sun, and tonight Neptune is near the moon on the sky’s dome, likely drowned in its glare. What you can do tonight is use the moon to get a feel for the whereabouts of Neptune in our sky. Plus, you might be able to glimpse the zodiacal constellation Aquarius in the starry heavens.
Neptune lies within Aquarius’ boundaries now, and Aquarius lies to the north of the bright star Fomalhaut, which will be visible tonight – despite the moonlit glare.
The ecliptic – roadway of the sun, moon and planets in our sky – passes right through the constellation Aquarius. Practiced sky gazers know that the planet of our solar system must reside on or near the ecliptic on our sky’s dome.
And right they are, for Neptune will be close to the 5th-magnitude zodiacal star Sigma Aquarii for the rest of this year.
Sky chart showing the star Sigma Aquarii
This star, Sigma Aquarii, is visible to the unaided eye as a faint speck of light in a dark country sky. This chart from skyandtelescope.com provides the telescopic field of view and can help you find Neptune … once the moon moves away.
Neptune reigns as the most distant full-fledged planet in the solar system, since Pluto was reclassified as a dwarf planet by the International Astronomical Union (IAU) in 2006.
Pluto wasn’t denied planetary status because it’s not massive enough to be a planet. Believe it or not, Pluto – in and of itself – has sufficient mass to qualify. Rather, Pluto was reclassified by the IAU because this world doesn’t have the heft to “clear the neighborhood around its orbit.”
Pluto, by the way, is locked into a 2:3 orbital resonance with Neptune. For every two times that Pluto circles the sun, Neptune circles the sun three times.
Beyond Neptune, there are a number of trans-Neptunian objects – called plutinos – that are also locked into a 2:3 orbital resonance with Neptune.
Bottom line: Tonight – September 25, 2015 – the moon passes fairly close to Neptune on our sky’s dome. Once the moon leaves the evening sky, by late September or early October, try locating Neptune in front of the constellation Aquarius, and near the star Sigma Aquarii. Be forewarned. You’ll need an optical aid, and probably a good sky chart plus lots of patience to see this faint and distant planet.
EarthSky astronomy kits are perfect for beginners. Order yours from the EarthSky store.
Help support posts like these at the EarthSky store. Fun astronomy gifts and tools for all ages!
Everything you need to know: Harvest Moon 2015
Super Blood Moon eclipse this coming Sunday night!
from EarthSky http://ift.tt/1OxMtKP
Tonight – September 25, 2015 – don’t expect to see the planet Neptune. Even on the darkest of moonless nights, you need an optical aid to see Neptune, the eighth planet outward from the sun, and tonight Neptune is near the moon on the sky’s dome, likely drowned in its glare. What you can do tonight is use the moon to get a feel for the whereabouts of Neptune in our sky. Plus, you might be able to glimpse the zodiacal constellation Aquarius in the starry heavens.
Neptune lies within Aquarius’ boundaries now, and Aquarius lies to the north of the bright star Fomalhaut, which will be visible tonight – despite the moonlit glare.
The ecliptic – roadway of the sun, moon and planets in our sky – passes right through the constellation Aquarius. Practiced sky gazers know that the planet of our solar system must reside on or near the ecliptic on our sky’s dome.
And right they are, for Neptune will be close to the 5th-magnitude zodiacal star Sigma Aquarii for the rest of this year.
Sky chart showing the star Sigma Aquarii
This star, Sigma Aquarii, is visible to the unaided eye as a faint speck of light in a dark country sky. This chart from skyandtelescope.com provides the telescopic field of view and can help you find Neptune … once the moon moves away.
Neptune reigns as the most distant full-fledged planet in the solar system, since Pluto was reclassified as a dwarf planet by the International Astronomical Union (IAU) in 2006.
Pluto wasn’t denied planetary status because it’s not massive enough to be a planet. Believe it or not, Pluto – in and of itself – has sufficient mass to qualify. Rather, Pluto was reclassified by the IAU because this world doesn’t have the heft to “clear the neighborhood around its orbit.”
Pluto, by the way, is locked into a 2:3 orbital resonance with Neptune. For every two times that Pluto circles the sun, Neptune circles the sun three times.
Beyond Neptune, there are a number of trans-Neptunian objects – called plutinos – that are also locked into a 2:3 orbital resonance with Neptune.
Bottom line: Tonight – September 25, 2015 – the moon passes fairly close to Neptune on our sky’s dome. Once the moon leaves the evening sky, by late September or early October, try locating Neptune in front of the constellation Aquarius, and near the star Sigma Aquarii. Be forewarned. You’ll need an optical aid, and probably a good sky chart plus lots of patience to see this faint and distant planet.
EarthSky astronomy kits are perfect for beginners. Order yours from the EarthSky store.
Help support posts like these at the EarthSky store. Fun astronomy gifts and tools for all ages!
Everything you need to know: Harvest Moon 2015
Super Blood Moon eclipse this coming Sunday night!
from EarthSky http://ift.tt/1OxMtKP
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