The Wild 2 Comet

Plenty of comets surround our solar system with some of them being known and active while others are not so active or periodic which is why we know little about them. Some of these comets have been discovered centuries ago as well such as the Halley’s Comet. On the other hand, a few are more recent discoveries such as The Wild 2 Comet which was discovered in 1978. The Wild 2 Comet has pretty interesting facts which are discussed in this article.

Overview of The Wild 2 Comet

The Wild 2 Comet is officially named 81P/Wild and is a comet that was discovered by Swiss Astronomer Paul Wild, from where it got its name as well. The date of discovery of this comet is 6th January 1978. By this time, there weren’t as advanced telescopes and equipment as we have today. However, a basic observation was done using a 40cm Schmidt Telescope located in Switzerland. Other names of The Wild 2 Comet include 1978 XI, 1984 XIV, and 1990 XXVIII as well.

It is considered among the famous comets of our solar system (Link here to the main post) because it returns after every 6 years making it one of the most actively visible comets. Another reason why it is considered quite significant is because of the missions sent by NASA to this comet to collect some particles from the comet’s coma. Apart from the moon, Wild 2 is the only celestial object whose particles have been brought back to Earth.

The Wild 2 Comet is expected to be over 4.5 billion years old. The orbit was more distant and circular for The Wild 2 Comet. However, in 1974, it passed within one million kilometers of Jupiter. As a result of the strong gravitational forces of planet Jupiter, the comet disoriented from its actual orbital path and moved in a bit closer. Previously, the orbit period of this comet was 43 years. After the 1974 incident and change of orbit, the orbital period is now 6 years only. Studies have concluded that this comet has a perihelion point of 1.59 Astronomical Units. After the change of its orbital path, the comet is now regarded as a fresh comet.

Wild 2 Comet observed from Earth

Shape of the Wild 2 Comet

As long as the dimensions of the Wild 2 Comet are concerned, they are 5.5 km × 4.0 km × 3.3 km. The comet presents the shape of a round object with depressions and uneven structure on all its sides. Many believe that the Wild 2 Comet is circular but it is not like that. The density of Wild 2 Comet is 0.6 g/cm3 which is 37 pounds per cubic foot while the mass is 2.3 x 1013 kg. The comet is smaller compared to many other comets in our solar system. However, being close to our planet, it becomes one of the most intriguing and studied celestial objects as well.

Apart from that, the photos taken by NASA’s Spacecraft Stardust revealed that Wild 2 Comet had sheer walls, flat depressions, and small to medium-sized topographical features. With a diameter of 5 kilometers, there are a number of impact craters and gas vents on this comet too which have resulted in the formation of the certain shape in which we see Wild 2.

NASA’s Mission to Wild 2 Comet

There have been several observations associated with the Wild 2 Comet. As this comet has a short orbit, NASA was able to send spacecraft to it as well. The first spacecraft sent in space to collect particles of a comet was called “Stardust” and was launched on 7th February 1999. The aircraft took almost 5 years to reach Wild 2 Comet upon which it was able to collect particle samples as well as close-up pictures of the comet.

The Stardust spacecraft was easily able to enter into the orbit of Wild 2 and collect the particles with the help of an Aerogel Collector. Aerogel is the lightest known solid and has the ability to collect fragile particles without any damage. Since the comet and its close fragments would be at high speed, Aerogel would simply bury itself in the material as soon as a high-velocity dust particle hits it.

During this collection, the spacecraft only entered the comet’s coma and not the comet itself due to limitations in landing technology. Stardust flew at a distance of 146 miles from the comet at a speed of 13,600 miles per hour. Once Stardust collected the dust particles and photographs, it was important to get this important data back to Earth.

“Sample Return Canister” was an important piece of equipment in Stardust that was installed to send the required samples back to Earth. Stardust released the sample return canister after it seemed fit and reached Earth in 2006. On 15th January 2006, the Sample Return Canister landed in UTAH and was in perfect condition with all the samples accurately stored. Scientists at NASA then collected the samples and sent them globally to 150 top astronomers and biological scientists to study the particle matter.

Illustration of StarDust close to Comet Wild 2.

Observations of the Wild 2 Comet

There have been several observations by scientists all over the world who were studying Wild 2. Initial findings suggested that the particles had different types of organic compounds including biologically usable nitrogen. Few pure carbon particles were also observed in the Wild 2 Comet’s particles which implied that there might be more of them but due to the limitation of the collection of particles, only a limited amount of carbon particles are seen.

Additionally, olivine, anorthite, and diopside were three important crystalline silicates that were found in the particles of Wild 2 Comet which showed that the temperature of this comet has been high. These three silicates only form at high temperatures. It was speculated that the high temperature could be because of reduced distance from the sun and a relatively shorter orbit period. It could also be because the comet was approaching the sun closer once again.

Other important minerals found include Indigenous aliphatic hydrocarbons which are mostly used in burning stoves or engines, normally. It also clearly showed the presence of Hydrogen and Carbon in the Wild 2.

In 2008, further observations and studies were conducted on the particles of the comet and found out oxygen isotope signature which suggests that there has been rocky material between the center and edges of the solar system.

By 2011, scientists from the University of Arizona were able to provide evidence of the presence of liquid water on this comet. They found that iron and copper sulfide were there and one way this is possible is due to the presence of water. One description also suggested that the comet is possibly a mix of “fire and ice” at the same time. However, more studies are required for further conclusive description.

From the studies, scientists were also able to find glycine. Glycine is an amino acid that creates proteins inside the human body. The presence of glycine showed that there might be some form of life on Wild 2 Comet.

About the Discoverer – Paul Wild

Professor Paul Wild

Paul Wild was a Swiss astronomer who was born on 5th October 1925 near Zurich. Wild was always a keen fan of mathematics, physics, and the study of celestial objects and bodies. For this reason, he pursued his career in the said fields. Initially, he studied at ETH Zurich after which he worked for the California Institute of Technology between 1951 and 1955. During this time, he was able to study the solar system in a much closer manner while researching many galaxies and supernovas.

Wild 2 Comet was not the first comet discovery by Paul Wild, Instead, it was the discovery of C/1957 U1 in the year 1957. By 1980, he became the director of the Astronomical Institute of the University of Berlin and stayed in his position for 11 years. Professor Wild passed away in 2014 at the age of 88. During his life, he was able to observe 4 periodic comets, 3 parabolic comets, multiple asteroids, and 41 supernovas as well. However, Wild 2 Comet is his most recognized discovery.


The Wild 2 Comet is surely an interesting one as it has a very short orbit period. NASA has plans to further study this comet and see how well it provides us with an idea of celestial bodies, solar systems, and various other fields of astronomy as well. The Wild 2 Comet is likely to come at the Perihelion in December 2022 and then in 2028. If it passes close to the earth, it will be visible to the naked eye as well.