Seeing Pluto

Debate over its planetary status aside, is it possible to actually see the planet Pluto using astronomical instruments commonly available to amateur astronomers?


By: Vanessa Uy


Mysterious Pluto managed to acquire “Page Six” supermarket tabloid-style popularity during the last few years. Mostly due to the International Astronomical Union’s somewhat hasty dethronement of its planetary status, thus inciting a populist uprising of a significant portion of planet Earth’s population. But to an amateur astronomer lucky enough to own an 8-inch reflector, chances of seeing this far-off real estate of our Solar System is now a possibility.

For some amateurs, seeing Pluto first hand via their own telescope can be a transcendental experience. Not unlike that of experiencing a live performance of "Beethoven’s Ninth” first hand. For others – like me – glimpsing it’s feeble light means creating your very own cherished memory. Especially if the most advanced digital camera you happen to own doesn’t have enough resolution to capture your “Pluto Moment” and post it on the Internet.

After the older members of our astronomy club had their “Pluto Moment” via their 8-inchers back in 1998. Using the star Zeta Ophiuchi as a guide star to find it back then. By the way, Zeta Ophiuchi is the bright middle star in the row of three at the bottom of the constellation of Ophiucus the serpent handler. Pluto’s current position on the latest Telrad Finder Charts puts it within the field of the constellation of Sagittarius, where it will remain until 2023.

As a consequence of our Earth-based vantage point, Earthbound astronomers will always see Pluto initially describes typical annual loop formations – which in this region of its orbit – averages around 2 ½ degrees across measured from Eastern to Western stationary points. The loops gradually open out into zigzag formations as Pluto approaches and then crosses the ecliptic – i.e. the apparent path of the Sun through the Zodiac as seen from our earthbound perspective. The helical nature - though it looks more like a squashed spring stretched sideways - of Pluto’s loop formations – which resembles a stretched spring – is a consequence of its steep – 17 degree - orbital inclination to the ecliptic. Coupled with the fact that Pluto is currently on the descending half of its orbit. Pluto’s opposition magnitude or brightness as seen from the Earth’s surface fades during the 16-year period – i.e. between June 2006 and July 2022 – from +13.9 to +14.3.

With Pluto’s magnitude fast approaching +14.0, you should be able to spot it with an 8-inch reflector from a dark observation spot, preferably one not plagued by urban light pollution. Once you become familiar with the Sagittarius constellation star field at medium power, crank up the magnification past 150x. An even higher power is better still, if the seeing conditions are good – i.e. the night sky is not shimmering like the air over a barbecue grill – or if your telescope’s optics is up to the task. Higher magnifications will darken the background, making Pluto more than just a faint flicker.

Even though blink comparators for amateur astronomers isn't yet widely available, the best way to confirm your very own observation of Pluto is to look for it twice – preferably a few days apart. You could decide to sketch the field with stars slightly dimmer than 14th magnitude. Use the second night’s observation to see which star has moved against the distant background stars. A broad V-shape of 8th to 9th magnitude stars can be used to anchor your sketch. Some newer telescopes are even equipped with a built-in LCD combining display with memory function. Which allows you to save your sketch into your telescope. To display their handicap prowess, some amateur astronomers who served as US Army or USMC snipers during Operation Desert Storm even masked down their 8-inchers while trying to find Pluto with less than 4 inches of available aperture.

My first hand experience – or is impression more apt - of “seeing” Pluto is that it looks like a pale blue robin egg colored star. From the eyepiece of my 8-incher with the magnification set at 150x – assuming that it’s chromatic aberration is invisible to my own eyes – Pluto does look different when compared to other stars within the Sagittarius star field. You can somewhat tell – assuming your own visual acuity is up to it – that Pluto merely reflects light from a primary source like our Sun. As opposed to the distant stars which can generate light by themselves. If an amateur astronomer has the ability to spot Pluto with his or her own 8-incher, and can do this with handicaps like masking their telescope to reduce available aperture. Then maybe they should consider becoming pros.