One of the celestial bodies that has always remained elusive and quite enigmatic in our Solar System for many years is Pluto. Nestled way beyond Neptune, Pluto has been a major subject of intrigue, fascination, and controversy among astronomers, experienced and amateurs alike.
Its demotion from its fully-fledged planetary status in 2006 by the IAU (International Astronomical Union) only fueled the controversy and intensified all the mystery surrounding it. More and more amateur astronomers have since wanted to have a glimpse of the dwarf planet.
While Pluto is quite elusive and difficult to spot in the sky, you can still observe it with a decent telescope. In this article, I will be telling you how to see Pluto with a telescope, the best way to find it in the night sky, and factors you need to consider when setting up your vantage point on Earth to view it.
Peering through our Solar System to observe this distant celestial object is quite a thrilling undertaking that most definitely deepens our appreciation of our mysterious universe.
Facts about Pluto
Pluto, a rocky world that is about 2390 kilometers in diameter, is one of the five dwarf planets in our Solar System. Before 2006, Pluto was considered one of the nine planets of the Solar System.
But in August 2006, it was demoted from its fully-fledged planetary status and considered a dwarf planet by the International Astronomical Union.
Now, what is a dwarf planet? You may wonder. In simple terms, a dwarf planet is a planet that failed to entirely clear its own orbit of any debris.
You see, when planets were forming, they got bigger by attracting rocks and any other debris around them, especially those in their orbit. Pluto failed to do that.
Scientists discovered that the orbit of Pluto is littered with a lot of rocks, some of which are almost as big as itself. This is the reason the IAU demoted Pluto to dwarf planet status in 2006 when the discovery was made.
According to the IUA, for any celestial body to be considered to be a planet, it must satisfy the following three conditions:
- The object must be orbiting a host star, and in this case, we are talking about the Sun.
- The body’s gravity must be massive enough to pull debris into a spherical shape.
- It must be the dominant object in its orbit. This simply means that the object must clear any objects such as rocks in its orbit.
We see that Pluto meets the first two conditions, but it hasn’t cleared its orbit of debris and rocks. It is, therefore, not considered a planet.
Pluto has five moons, the largest of them called Charon.
Charon itself is more than three-quarters the size of Pluto. The dwarf planet is more than 5.9 billion kilometers from the Sun but ventures closer to the Sun than Neptune does.
Its distance from our planet Earth is over 5.09 billion kilometers.
How to Find Pluto in the Night Sky
Before you start observing Pluto from Earth, you first need to find its position in the night sky. Note that because the atmospheric conditions keep changing and the fact that Pluto comes to the opposition every 367 days, the dwarf planet is not always up in the sky.
You, therefore, need to be sure it is up before setting up your equipment to view it.
One of the ways to do that is to use constellations, but if you are not good with that, there is a better and easier way. There are many astronomy applications and software available today that you can use to get the position of any celestial objects in the sky at any one given time.
Examples of these applications and software include Stellarium, Saky Safari, and Star Walk 2.
Most of these applications will give you a sky plan, depending on your location. They will also give the time and altitude of the planet so it is easy for you to trace and spot it.
You can also use various star charts available online to track and locate the dwarf planet.
Can You See Pluto without a Telescope?
It is impossible to see Pluto from Earth without a telescope for various reasons. One of the major reasons this is the case is the massive distance between Pluto and the Sun.
With more than 5.9 billion kilometers between the two, Pluto doesn’t have much light to reflect, so we can clearly see it from Earth. Planets like Venus, Jupiter, and Saturn are easily visible from Earth because of their close proximity to the Sun, so they shine bright and are easy to spot.
The second factor that makes it difficult for us to see Pluto from Earth is the distance between us and the dwarf planet. There are more than 5 billion kilometers between us.
While Pluto still reflects some light from the Sun, the distance is just too huge for us to see it without any decent equipment.
Another factor is its size. At just 2390 kilometers in diameter, Pluto is smaller than our Moon. This, coupled with its distance from the Sun, means it is just not going to reflect enough light for us to see it with the naked eye from Earth.
In general, Pluto lies at the very edge of our Solar System. It is small and shines at a small magnitude of just 14.4.
You are, therefore, not going to see it without a telescope. To get the best shot of the dwarf planet, you will need a telescope with a decent aperture, dark skies, and some patience.
How to See Pluto with a Telescope
Before we dive deeper into this section, I must mention that you need at least a 5-inch telescope to see Pluto. You stand a better chance if you have an 8-inch or bigger telescope. If you have one of these, it is time to observe the dwarf planet. But how?
As discussed above, you first need to locate the position of the planet in the sky. Download and install any astronomy application on your phone.
There are so many of them out there for both Android and iPhone. Once you have this ready, run then and search for the location of Pluto. If it is up in the sky, most of these applications will give you a sky map and the altitude of Pluto.
For example, the software can tell you the dwarf planet is 43 degrees west of the Eastern horizon. This, of course, will depend on your location.
Now, you need to use this information to get the exact location of Pluto in the sky. However, you are going to need a star chart including stars with a magnitude of between 14 and 15.
Note that the horizon itself will be the baseline, meaning it will be at 0 degrees. The zenith, directly overhead the horizon, is at 90 degrees. This tells you that midway through the zenith and the horizon is at 45 degrees. You can, therefore, locate Pluto at 2 degrees below this midway line.
When you know where to point your scope, set it and make sure the finderscope is correctly aligned. Point it to the direction established and look through the eyepiece to try and find Pluto.
You are going to need a lot of patience. One of the good things about dwarf planets and fully-fledged planets is that, unlike stars, they move.
This fact is going to come in handy later. When you look through the eyepiece, you are going to see stars, some of which are faint. Pluto should be among the faint ones, probably the faintest one.
Now, all you need to do is plot the position of this faint ‘star’ for two to three consecutive nights. Pluto moves about 1.5 arc minutes per day.
With a magnification of between 200X and 250X, you should be able to see the faint ‘star’ change its position daily. This is how you know you have Pluto in your view.
When Can I Observe Pluto with a Telescope?
As I pointed out earlier in the article, Pluto is best seen when it is in opposition. This is when it is directly opposite the Sun. Pluto reaches opposition every 367 days, and for the foreseeable future, this is going to be in late July of every year.
However, this is not to say that you cannot see Pluto during other times. While it is trickier than when it is in opposition, you can see Pluto from March through October when it is far enough from the Sun.
Most stargazers with a good telescope are able to spot the dwarf planet during this period.
If you are far away in the North, it is even harder to see Pluto when it is not in opposition. Your best time to see it will be during the summer months when it barely appears above the horizon, much like the Sun does during winter.
What Size of Telescope Do I Need to View Pluto?
This dwarf planet is gradually drifting farther and farther away from the Sun, and, as a result, it is getting dimmer and dimmer, making it more difficult to see from Earth. At its perihelion in 1989 (29.6 AU), Pluto shone at a magnitude of 13.7.
During this time, Pluto was as bright as the moons of Uranus and Neptune. It was visible with any telescope with apertures as small as 4 inches.
The dwarf planet has since drifted farther away from the Sun. At present, its brightness hovers around a magnitude of between 14.3 and 14.4.
That said, today, you can only observe Pluto if you have a telescope with an aperture of at least 5 inches.
However, you will have the best shot at seeing Pluto if you have a telescope with an aperture of 8 inches or bigger. You will still need dark skies to get the best images, and as we will see later, there are other factors that play a significant role in the quality of images you get.
With a 10-inch telescope, you can conspicuously see Pluto under darker skies. You will need a larger telescope if you live in an area with a lot of light pollution.
A 12-inch scope offers better images with less struggle, and a scope with a 14-inch to 16-inch aperture will do a great job and give you clearer glimpses at Pluto.
What Pluto Looks Like in a Telescope
Through most telescopes, Pluto appears as a star-like spot. Its disk is below 0.1 arc seconds wide, and no telescope is able to resolve it. This begs the question: How am I going to know I am looking at Pluto?
I explained earlier that the best way to know you are looking at Pluto is by sketching its position in the sky against the background stars. The dwarf planet moves about 1.5 arc minutes per day, so if you notice the star-like point changing its position over 2-3 nights, then you can confirm you are actually looking at Pluto.
You can also familiarize yourself with the star field immediately around Pluto and use high magnification to make sure you are looking at Pluto at any given time.
Factors to Consider when Viewing Pluto with a Telescope
There are a few factors you need to consider when choosing your vantage point to view Pluto from Earth.
You want to make sure you have the right ‘seeing’ conditions. You probably already know that the atmosphere is filled with a lot of gases that keep moving and swirling around. This and other things, such as air turbulence, can affect the seeing conditions.
There are many resources and astronomy communities online you can use to know if the conditions are right to see Pluto.
Air turbulence also affects the quality of images you get. Be sure to avoid setting your observation point in areas that could potentially emit heat into the atmosphere in the evening.
Examples include areas with concrete floors and close to chimneys or rooftops.
Also, choose places with the least amount of light pollution. Again, you can use online communities, forums, and astronomy applications to find out which places have the least amount of light pollution around your location.
While Pluto is very far away from us and one of the dimmest celestial objects, we can still see it from Earth with a telescope. You will need at least a –inch telescope to see Pluto.
Follow the tips provided in this guide and enjoy the sight of Pluto.