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Mission to Uranus – Uranus at opposition – Our Wide Sky

Mission to Uranus – Uranus at opposition

October 18, 2017

This week the planet Uranus is at opposition. I'm on a mission to see it!

There is talk around that Uranus will be bright enough to see with the Naked Eye. This is really exciting. Normally we can only see the planets known as the "Naked Eye Planets", and Uranus is not one of them. So Naked Eye viewing is a pretty big deal.

[Mission Log Updated to October 28 (Spoilers: cloudy!)]

What does opposition mean?

As all the planets, orbit the sun they become easier or more difficult to see from Earth, depending on the where we and they are in our orbits. 

There are two planets that orbit the sun inside our orbit, Mercury and Venus. They don't have oppositions, because we are never between them and the Sun.

When a planet is on the other side of the sun we can't see it at all. We call this a conjunction.

Planets at Opposition

For all the outer planets there is a time where the Sun, Earth and the planet is lined up. At this time the planet is as close to Earth as it will get, and it is the easiest to see that it will ever get. This is opposition.

The diagram is from Wikipedia and it describes nicely the different positions. You can see that during opposition the planet is closest to the Earth and we will therefore get the best view.

On October 19th Uranus is at Opposition. It is still a very long way away.

So can I see it?

This is the best chance we'll get to see Uranus with the Naked Eye. It is at opposition on a moonless night. 

That doesn't mean it will be easy. Here are the things that need to line up to be able to see something with the Naked eye:

  1. You need a clear sky. Clouds, haze, seaspray, fog, high humidity - all of these things will ruin your night.
  2. You must be able to see in the direction of the object. You can't see through trees and buildings.
  3. The object needs to be bright enough for the Naked Eye. A magnitude of about 5-6 is about as dim as you will be able to see with the Naked Eye.
  4. You need to know where to look. Finding dim objects is a challenge. Knowing exactly where to look helps.
  5. You need a dark sky.

It will still be magnitude 5.68 (remember that the bigger the number the dimmer the object), which is just on the edge of being visible with the Naked eye. You'll definitely need a dark sky to see it.

City dwellers will find it almost impossible.

Mission to Uranus

From my position in a southern Sydney suburb I can see the sky, but there are plenty of things that get in the way of a good observation.

  • My view to the North is over the main part of Sydney. This means that anything on the Ecliptic is going to be washed out by light spilling up from streetlights, construction lights, traffic, houses, appartment buildings, sports fields.
  • My view to the North East is right across Sydney Airport. This is also close to Botany Bay, and not far from the coast and the sea-spray in the air catches the light from the airport. Airports are pretty good with down facing lights, they make less glare for pilots, but there is still a massive amount of light going up, and the sea air creates a big orange bubble of light over the airport.
  • I have a big old Tallowwood tree that gets in the way of about a quarter of my sky. 

I know that I won't see Uranus from my backyard with my unaided eye. But I definitely want to try for binoculars and certainly with my telescope.

My first problem - knowing where to look. 

At this opposition Uranus is located in Pisces. Right near Omicron Pisceum. This is a pretty dim star at 4.27, which will make it nearly impossible in my backyard sky.

Tallowwood tree

Even finding Pisces will be a challenge. The brightest star in Pisces is only 3.62 magnitude, and it appearing to my North East. I don't really have any chance of even knowing where to look with my naked eye.

I've checked my star charts. Mid evening, between 9 and 11pm local time, Pisces will be in that patch of sky over our garage. That is where I have to look.

Mission Log - Mission to Uranus

October 17, 2017

Plan: Just get out and look for Pisces with binoculars.

Weather: High cloud, wind.

Sky quality: Light reflecting off haze over the city.


  • No stars visible to naked eye in the area toward Pisces.
  • No visibility to Pegasus which would have pointed toward Pisces.
  • Even with binoculars there was no identifiable stars, due to lack of reference.
  • Using Skymap app on my iPad I confirmed that I was looking in the right direction.

Summary: This attempt was a failure. I could not even see the constellation Pisces.

October 19, 2017

Plan: View Uranus with the telescope. Image if possible.

My star chart (created from Cart du Ciel)

Uranus Opposition - star chart

Observations: Clouded out. No visibility all night.

October 20, 2017

Plan: Check weather. Not expected to clear until tomorrow.

October 21-23, 2017

Plan: Weather expected to clear. Take telescope to a park with good light conditions.

Well that plan didn't happen either. The sky was expected to be clear on Saturday night and it was clear early, but then the cloud came in. Same happened on Sunday night.

Monday night was beautiful, but a previous engagement meant that I could not take advantage of it.

October 24, 2017


  1. Try again for Uranus late.
  2. Try to capture the Moon after sunset.
  3. A faint fuzzy (The Wild Duck Cluster - To be confirmed) is visible early evening so I will try to photograph that as well.

October 24 - October 28

Observers log: Cloudy. Cloudy. Cloudy. Cloudy. Cloudy.

Not even the opportunity to capture the waxing cresent Moon. 

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