Kuiper Belt Objects

The region beyond the orbit of Neptune (30-50 AU from the Sun) is what is now referred to as the “Kuiper Belt“ which contains numerous bodies and material remnants from the formation of our solar system. Unlike the “Asteroid Belt” in which the bodies are predominately rocky in composition, Kuiper Belt Objects are more icy in nature and contain large proportions of frozen water, methane, and ammonia. This region is thought to be the point of origin for most comets as well as some of the moons which orbit the outer planets of Neptune and Saturn. 

The total mass of objects that make up the Kuiper belt is estimated to be no more than 10% of the mass of the Earth and the average distance between objects greater than 100 meters in size is on the order of 1 AU (93 million miles).  This can be contrasted to the density of the asteroid belt which has an estimated mass of 1/2,000th that of Earth with an average spacing of objects on the order of 600,000 miles – over twice the distance from the Earth to the Moon.

Here is a graphic showing the relative sizes of the largest known Kuiper Belt Objects showing their sizes relative to the Earth and the Moon. (Johns Hopkins University Applied Physics Laboratory). To date I have been able to photograph and track the four largest objects.
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Pluto

Once considered to be the ninth planet in our solar system, Pluto was reclassified as a “Dwarf Planet” by the International Astronomical Union (IAU) in 2006.  It is certainly the most well known of what we now call Kuiper Belt Objects or Trans Neutonian Objects (TNO’s) and may or may not be the largest – it is very close in size to Eris.  Pluto has the appearance of a 14th magnitude star due to its average distance from the sun of 3.7 billion miles (40 AU) and has a diameter of  only 1,473 miles.  It has five moons with the largest (Charon) being nearly half the size of Pluto itself.

Photos show movement of Pluto over a three day period. Click on the panels for a larger view.

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Here is a composite of three photos taken on three different days that shows Pluto’s movement against the background stars from Aug 13 to Aug 23, 2018. It takes 247 years for Pluto to make a complete orbit around the Sun.
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Eris

Discovered in 2003 Eris is the second largest Dwarf Planet. It is similar in size to Pluto (about the size of our Moon) but it is the more massive of the two which indicates that it is more rocky in composition with less ice. It is located three times further away from the Sun than Pluto with an orbital period of 557 years. Shining at magnitude 18.9 it is 90 times fainter than Pluto. Eris has one small moon named Dysnomia. At magnitude 18.8 it is near the limit of my imaging capabilities.


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Makemake

(Pronounced Mah-kee-mah-kee) Discovered in 2005, Makemake is the third largest Kuiper Belt Object at 2/3 the mass of Pluto. While it shines at 1/5 the brightness of Pluto it is the second brightest Kuiper Belt Object. It has an orbital period of 305 years and has one small moon.


This photo and the following two show the location and movement of Makemake over a period of four days.
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Note the movement of Makemake over a period of 22 hours from the previous photo.
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And after another two days…..
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Haumea

(Pronounced Haa-mah-uh) Discovered in 2004, Haumea is the fourth largest Kuiper Belt object (1/3 the mass of Pluto) orbiting the Sun at an average distance of 43 AU with a period of 283 years.  It is thought to be oblong in shape and has a small ring system as well as two small moons.

The photo above shows the motion of Haumea over the course of several days.
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