Neptune sits nearly 5 billion kilometers away from our comparatively diminutive planet. Through a moderate sized backyard telescope it looks like an ordinary star. However, if the seeing is good and you bump up the magnification you can see it has a disk. It was very early on a summer morning in 2016 that I attempted to find Neptune. I studied Aquarius in my star charts for at least 15 minutes determining to find λ Aquarii. Neptune was only a half degree away from this naked eye star. I did not have a red dot finder working at this time so I relied on a straight through finderscope. It took 5-10 minutes to find λ Aquarii in my telescope. I used my 25mm eyepiece with a 62.5' field of view. I saw a dim grey object that did not twinkle among a few stars. It was Neptune. Amazingly I was able to capture it with my cell phone camera and the image is shown below.
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| Neptune |
It may not look like much but it was hard work and determination that produced this blob of light. Over the course of the next few months I watched as Neptune moved a few arcminutes each day. It became a daily tradition when the sky was clear I would sketch the location of our furthest planet. A log of the orbital motion is shown below.
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| Neptune - Orbital Motion |
Neptune is named after the Roman god of the sea and its largest Moon is Triton. Its radius is nearly 4 times that of Earth and its mass is 17 times. It takes 164 Earth years to orbit the Sun, so in our lifetime we will only see it traverse half of its orbit. It is interesting to note that its rotation is comparable to that of Earth. Neptune rotates once every 16 hours. Rings were discovered around the planet when I was two years old back in 1984.
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