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Neptune Opposition

A personal viewing log


My sorry attempt at a Neptune photo with an iPhone through a very hazy atmosphere.

I had a great night of viewing last night, even though the atmosphere was hazy. There was a first quarter moon, Neptune was in opposition and my neighbors were’t home!

I set up my telescope in the early evening so the kids could see the moon and so I could dial in the Telrad and finder scope. The bottom center of the moon has some really intense cratering, so when it’s at a quarter phase (half lit), all kinds of cool stuff is visible at the terminator.

I snapped some shots of a complex crater about 1/3 up from the bottom with my iPhone. I don’t have a fancy rig for taking photos, but the iPhone does okay on bright objects like the moon. I can’t track down the name of this crater, but I watched it for most of the night.

The rim cast a shadow across the bottom of the crater, while the uplifted center cast it’s shadow about half way up the opposite side. As the atmosphere ebbed and flowed, different parts would come into focus and I could see layers in the illuminated crater wall. As the night went on, I swear I saw the shadow from the uplifted center recede to the foot of the wall. That is lunar rotation1!

As I was waiting for Neptune to rise over the tree line, I thought I would try out some of my filters on some nebula. I had a nice, comfortable angle for my chair at the eyepiece so I decided to stick to objects near the ecliptic (the line in the sky where the sun and moon pass overhead). The Lagoon and Trifid nebulae are right next to each other, and were in my line of sight. I could pick them both out with my naked eye2. I used my 9mm eyepiece which gets me about 140x magnification to get a tight view of them. I then switched to my 2" 33mm eyepiece (~38x). I really like the wide field of view with that eyepiece, but it didn’t quite get me as close as I wanted to be.

I recently got a 2" barlow lens, so I tried that. It got me close enough, but the barlow requires you to line up your eye quite a bit more. The atmosphere was also pretty dirty and a lot of the detail was lost. I really need to get some new eyepieces.

At about 10:15 p.m. I saw that Neptune was high enough in the sky to get a nice view. At least I thought it was Neptune. I’m still pretty new to this, so I have trouble recognizing constellations. It can also be pretty light polluted in my area, so more subtle markers can be hard to see.

I use Star Walk on my iPhone quite a bit, and it has a calibration view that lets you superimpose the star field over what the camera sees. This is very handy for identifying objects, but the iPhone is so bright (even on its dimmest setting and with night mode on in Star Walk), it’s pretty useless for deep sky objects. It’s totally fine for planetary viewing, though. And I was able to confirm that it was Neptune I was looking at.

Neptune is 4.5 billion km from the sun, which is pretty damn far. I didn’t know quite what to expect, but it definitely had more of a sparkly star-like appearance than Mars or Jupiter. Some of that may have been due to the dirty atmosphere. It did have an easily recognizable bluish hue, and knowing that you are looking at something so huge and far aways gives you a palpable sense of awe.

I stayed out until Kristyn got home from hanging out with her friends at about 11:00 p.m., so I think I got a good 5 hours of viewing time in. Not having neighbors constantly flicking lights on and off, starting bonfires and screaming at each other in drunken rages was quite a nice break from the norm.

  1. And orbit too, I guess. Because the moon is in tidal lock with the earth, it rotates at the same rate that it orbits, and since it is orbiting us as we both orbit the sun, I suppose it isn’t only it’s rotation that effects moon days. “Mondays” on the moon last over 27 earth days. 
  2. While dialing in my view, I stumbled across M28 (a globular cluster) in my finder scope. It came out very clear with my urban sky filter.