What Are Some Strange, Unusual, Weird Objects in Our Solar System?

Updated on February 8, 2018
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Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly improve it.


While it would be easy to fill this article with a bunch of planets and moons, I decided to shift the focus to the lesser-known solar system objects that are strange and bizarre. Below is but a sampling that is out there. If you want another one explored here, please leave a comment and I will get on it. And now, enjoy!


1950 DA

This mile-long object really should be called objects, for it is not a solid body but a collection of rocks held together by gravity. That being said, it does have a fast rotation rate of one revolution every 2 hours which should be sufficient for it to fly apart. So why doesn’t it? Physicists from the University of Tennessee devised a solution in August 2015 after examining observations from NASA’s Wide-Field Infrared Survey Explorer. Using data from the telescope to construct a computer model, they suspect that weak electrical attraction between molecules of the rocks (which are as small as 2 meters) allows Van der Waal’s forces to play with gravity (Palus 17).

Body 288P
Body 288P | Source

Body 288P

This is a main-belt comet, also known as an active asteroid. That alone makes it unusual, because it blurs the line of distinction between asteroids and comets. They are asteroids that have comet-like features. What makes 288P even weirder is that it is a binary active asteroid, spinning apart and being pushed away from each half by gas torque. The are each roughly the same size and are currently 100 kilometers apart - and growing (Irving).



Where do we start? This was initially thought to be an asteroid upon its detection in 1977 but as the years went by it started to display a coma, just like a comet! But it was too big to be one, so is it from the Kuiper Belt? If so, how did it get knocked into its position so far away from the Belt? And the levels of variance in its brightness didn’t sync up with an object that far away. The majority of scientists classify Chiron as a comet now because of the majority of feature it displays but some feel otherwise. As always, this isn’t the end of the story.


2003 EL61/Santa/Haumea

This Kuiper Belt object (KBO) and dwarf planet was found on December 28, 2004 by Mike Brown and his Caltech team of astronomers and was for a short while nicknamed Santa for the proximity to that date. Soon, scientists realized that the light reflecting off of it wasn’t consistent. Every 2 hours, the brightness fluctuated by as much as 25%. That couldn’t be the rotation rate of the object, for it would fly apart! After looking at several models, it was determined that Haumea is shaped like a tapered off cigar and actually completing a rotation every 4 hours, still fast enough to be the quickest spinner in our solar system. It likely got this shape after a collision with another KBO, also producing the two known moons around Haumea (named Hi’iaka and Namaka), and giving the object the huge spin that stretched it out (Thompson, Coleman).


2002 UX25

Another KBO discovered by Mike Brown and the team, this one has an overall density less than water, meaning that if you could get an ocean big enough to fit the 650 km wide object, it would float. This fact isn’t surprising, for Saturn is also capable of floating, but UX25 is the largest solid body that can do it. The density was determined after using the moon around UX25 to find its mass and then based off stellar brightness readings the volume could be computed. Then the density is just mass over volume. But previous data shows that typically objects smaller than 300 km are less dense than water and anything greater than 800 is more, but UX25 is in that middle zone and is 18% less dense than water, placing it firmly in the camp of 100-200 km object behaviors. And that’s bad, because if larger KBOs are made of smaller ones which have less rock, then how can they have such high levels seen that help them achieve the observed density values? Scientists suspect UX25 might be an anomaly, but this is unlikely unless we have more data to back this up. Andrew Youdin (from the University of Colorado Boulder) and his coworkers suspect that instead of the traditional smaller-building-up-to-larger pieces scenario, current small KBO pieces are not leftovers from this process but are a result of collisions between larger KBOs (O’Neill, Cowen).


90 Antiope

It is common to find binary asteroid systems in our solar system. But in the case of 90 Antiope, it is uncommon to find two which are not only so close in mass but also in distance. It is because of this that scientists did not know that it was two different objects until observations from the Keck Observatory in 2000 (134 years after it was discovered) revealed it. Both are about 53 miles long and are about 101 miles apart. Because of its family (the Themis branch), the most likely explanation for its formation was a break-up, but it is likely a unique object because of the size similarity (Coleman, Michalowski).

2011 KT19/Niko

Located beyond Neptune, this mainly ice object is about 124 miles long. What makes it so unusual is its 110 degree orbit with the ecliptic and the retrograde motion it exhibits. Located by the Pan-STARRS 1 survey, it does not appear to be a part of the Planet Nine group of objects that seem to hint at an unseen object. But what else could something have caused such an unusual orbit? (Wenz 17).

Works Cited

Coleman-Smith, James. “10 Bizarre Objects You Didn’t Know Were in Our Solar System.” Listverse.com. Listverse, LTD., 05 Mar. 2015. Web. 19 Jun. 2016.

Cowen, Ron. “Astronomers Surprised by Large Space Rock Less Dense Than Water.” Nature.com. Macmillan Publishers Limited, 13 Nov. 2013. Web. 18 Jun. 2016.

Irving, Michael. “Hubble Spots a Strange New Type of Celestial Object.” Newatlas.com. Gizmag, 20 Sept. 2017. Web. 16 Jan. 2018.

Michalowski, T. et al. “Eclipsing Binary Asteroid 90 Antiope.” Astronomy & Astrophysics 423: 1160. Print.

O’Neill, Ian. “Strange Object Boots Kuiper Belt Mystery.” Discoverynews.com. Discovery Communications, 13 Nov. 2013. Web. 01 Jun. 2016.

Palus, Shannon. “Keep It Together.” Discover Sept. 2015: 17. Print.

Thompson, Andrea. “The Weirdest Object in the Solar System?” Space.com. Purch, 22 Jun. 2009. Web. 14 Jun. 2016.

Wenz, John. "Newly Discovered Solar System Object Unveils New Mystery." Astronomy Dec. 2016: 17. Print.

© 2016 Leonard Kelley


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