NEPTUNE REACHES OPPOSITION LATE THIS MONTH – WHAT’S THAT REALLY MEAN?
Photo By: Voyager 2.
On Monday August 26, at precisely 2129 EDT (0129 UTC on the 27th) the Ice Giant will reach opposition. Opposition by definition is when Earth is placed exactly between the Sun and a particular object which in this case is the planet Neptune. What that means for observers is that Neptune on the night of August 26, morning of the 27th will be at its highest point in the sky as it is directly opposite the sun. Also it’s as close as it will get to the Earth in this particular orbit so it will look its biggest and brightest (Each opposition the distances change slightly).
There are some things to consider here though if you plan to view the 4th largest planet. First and foremost it may be huge but it’s far away. In fact, at times Neptune is further from the Sun than Pluto is! Also, the Moon will be waning but gibbous. I believe it will be an age of 20 or 21 days old in its 29.53 day synodic cycle thus the already dim apparent magnitude of + 7.8 (Out of naked eye view) will be reduced significantly further. The tradeoff may be try again through the week as the Moons phase really wanes away and darkens the night.
At an average distance of 30.3 Astronomical Units (AU) or 30 times further from the Sun than the Earth is, during opposition it will be at a distance of about 29 AU and its angular dimensions a mere 2.4” arcseconds on the night sky. Keeping in mind 1 arcsecond is 1/3600th of a degree of sky.
If you don’t get a chance to view it this month don’t worry; it reaches opposition about 2 days later every year (every 367.5 days). All in all get out there and give it a go, especially if you know someone with a computerized go-to telescope or precise star charts and navigation skills. It won’t be much but you will be able to check the planet Neptune off your astronomy “bucket list”.
IN THE SKY page on this event: http://in-the-sky.org/news.php?id=20130827_14_100
Position of Neptune through 2023: http://www.nakedeyeplanets.com/neptune.htm
“THE SKY LIVE” Neptune Tracker: http://theskylive.com/neptune-tracker
Sky and Telescope page for this event: http://www.skyandtelescope.com/observing/highlights/Uranus-and-Neptune-in-2013-190064991.html
Earth Sky page for this event: http://earthsky.org/tonight/neptune-comes-closest-to-earth-for-the-year-on-august-26
Uranus & Neptune 2013: http://www.rasnz.org.nz/SolarSys/2013/2013UranNept.shtml