INTRODUCTION
How long would it take to reach each of the dwarf planets in the solar system? In the solar system, there are many interesting objects, such as planets, comets, asteroid belts, and natural satellites, but other objects do not fall into any of the above classifications; these are the dwarf planets. Do you want to know how many dwarf planets there are and how long it would take us to reach each of them? Let’s start!
WHAT IS A DWARF PLANET?
In 2006 the International Astronomical Union (IAU) had a meeting where the most important astronomers and astrophysicists participated. This important meeting was to clarify our definition of “Planet” once and for all. You may not know it, but the word “Planet” comes from the Greek ” planētēs” which means “wanderer” this is because centuries ago, it was thought that the Earth was the center of the universe and that everything revolved around us including the Sun and the moon. Among the stars in the sky, there were a few that moved strangely, since when looking at them every night and tracing their routes around the Earth, it seemed that were coming and going as if they had no fixed course, and because of this our ancestors called them wandering stars “Planets”. Over the years, science helped us understand that these celestial bodies were not stars but planets, like Earth. But the name “Planet” remained even though it’s meaning no longer fit with what the planets were. With the advent of telescopes and advanced planet-tracking technology during the nineteenth century, astronomers found the ninth planet in the solar system, Pluto.
HISTORY OF PLUTO
The problem with Pluto is that this planet was very different from all the others because it was extremely small, even smaller than the moon. This sparked a debate in the scientific community as they did not know whether to name this body a planet or not. Over time Pluto became so famous that for 70 years, everyone accepted the idea that Pluto was the ninth planet. But this began to change in the late 90s, as many astronomers began to be unhappy that Pluto was considered a planet. The reason is that there were other celestial bodies very similar to Pluto in the solar system that were not considered planets, one of them was Ceres, which until that time was considered an asteroid, but which was very similar to Pluto in size. Then in 2005, a team of scientists made up of Michel Brown, Chad Trujillo, and David Lincoln Rabinowitz discovered a new object in the solar system that they named Eris; this new object was practically the same size as Pluto. Along with Eris, the discovery of Haumea and Makemake was also announced, two other bodies that, like Eris, shared characteristics with Pluto. Then the community of astronomers ran into a big problem; all these new objects were similar to Pluto, and Eris was almost the same size. Were all these new celestial bodies to be classified as planets? If this were done, the solar system would no longer have only nine planets, but there would be 13 and maybe even many more since it was likely that objects similar to these would continue to be found scattered throughout the solar system.
The solution to this crossroads would come in 2006 when the International Astronomical Union (IAU) called on the world’s leading astronomers to redefine the concept of the planet. Until then, we had never needed to do so, but before discovering so many new objects that looked like Planets but were very small, a historic agreement was reached. It was established that for a celestial body to be classified as a planet, it must meet at least two requirements, these were:
- The object must orbit the Sun.
- The object must have enough gravitational pull force to sweep its entire orbit around the Sun, meaning that its orbit must be free of asteroids.
With this new definition, all new newly discovered objects were excluded, including what had been the ninth planet for many years, Pluto, since it did not meet the second requirement. A new definition was also invented to classify all these objects that were not Planets but were not Asteroids either; that’s how they were named Dwarf Planets.
CERES
Ceres is the largest astronomical object in the asteroid belt; this is a region of the solar system that lies between the orbits of Mars and Jupiter. Ceres has a diameter of about 945 km, being smaller than Pluto. Calculations indicate that the mass of Ceres is one-third of the total mass of the asteroid belt, being the only object in the asteroid belt to have reached hydrostatic equilibrium. Hydrostatic equilibrium is a point where pressure force and gravity reach equilibrium, giving celestial bodies a spherical shape. An interesting fact about Ceres is that when it was discovered in 1801 by Giuseppe Piazzi, it was tried to classify as a planet, but being so small, this idea was discarded. Ceres was long thought to be the remnant of a planet that had existed right between the orbit of Mars and Jupiter, but more recent research suggests that there has never been a planet in that region and that Ceres was always a minor object. Ceres is located between 2.5 to 3 Astronomical Unities approximately. Remember that an astronomical unit is equivalent to 93 million miles (150 million km); Ceres is located about 279 million miles from the Sun (450 million km). NASA’s Dawn space exploration probe is the only mission that has managed to pass near the orbit of Ceres, it was launched in 2007 and took 8 years to reach Ceres, but this is because the Dawn probe aimed to study other celestial bodies before and that is why it took longer to arrive. With modern technology we will take us between 2 and 2.5 years to reach Ceres if no setback occurs on the trip.
PLUTO
Among all the famous dwarf planets Pluto is more popular. Pluto, which was the ninth planet for a long time, is beyond the orbit of Neptune, precisely 40 Astronomical Units, which is equivalent to 3,670 million miles (5,906 million km). This distance is so great that a radio signal, which travels at the speed of light, takes more than 5 hours to reach Pluto from Earth. NASA’s New Horizons space exploration is the that has come the closest to Pluto. It was launched in 2006 and took about 10 years to reach the orbit of the dwarf planets. In 2016 the probe passed 7,767 miles (12,500 km) from the surface of Pluto and took the opportunity to photograph it and its 5 moons (Charon, Hydra, Nix, Kerberos, and Styx). The New Horizons probe used various gravitational assists to take advantage of the approaching gap between different celestial bodies. One of them was in 2007 when it had its closest approach to Jupiter. New Horizons performed a gravitational assistance manoeuvre taking advantage of the gas giant‘s intense gravity. Thanks to this, it saved 3 years of travel and reached Pluto in just 10 years. If we wanted to replicate the trajectory used by the New Horizons probe with a human-crewed spacecraft, we would have to get very close to Jupiter, which would be very harmful to astronauts due to the intense radiation surrounding the planet. However, using only rockets would take us more than 20 years to reach Pluto; gravitational assistance is the only way to reach the farthest planets so quickly. Unfortunately, this technique is riskier with human-crewed spacecraft, and until now, it has never been done.
HAUMEA
Discovered in 2003 by a team led by Jose Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, this dwarf planet is the third closest to the Sun. Although its shape has never been directly observed, calculations of its light curve suggest that it is ellipsoidal, with the central axis twice as long as the smallest, like an egg. This dwarf planet lies at a distance of 43 Astronomical Units, equivalent to 4,035 million miles (6,495 million km), is farther away than Pluto, and is much smaller. With the fastest spacecraft we currently have and taking advantage of the approach gaps between gas giant planets, we could shorten the travel time to 15 years using gravitational assists as the New Horizons probe did. But without gravitational assistance and only using our space rockets, the journey would last between 25 and 30 years. If you leave the Earth at the age of 30, you will already be an older man of 60 years by reaching Haumea.
MAKEMAKE
Discovered on March 31, 2005, by a team led by Professor Michael Brown of the astronomical observatory at the California Institute of Technology. This dwarf planet has also not been directly observed, but observations of its light curve suggest that it has reached hydrostatic equilibrium; that is, it is almost spherical. With a radius of 715 km, it is bigger than Haumea and has an area completely covered with methane and ethane in the solid state. Initially, this dwarf planet was nicknamed Easterbunny by its discoverers, as it had been discovered on Easter Week. Its definitive name, Makemake, corresponded to the creator god of Easter mythology and was chosen to maintain a relationship with the Pascua. Makemake has a very eccentric orbit. Sometimes it is very close and sometimes very far away; because of this, it is positioned at the fantastic distance of 53 Astronomical Units at its farthest point, better known as aphelion. This equates to 4.939 billion miles (7.95 billion km). So far, the only objects that have made it this far in the solar system have been the Voyager exploration probes, and it took them more than 30 years to get to that point using only gravitational assistance. If we only limit ourselves to using space rockets, a trip from Earth to Makemake would take between 35 and 40 years; that is, a round trip back and forth would take approximately 80 years, and it would be necessary to say goodbye to all your loved ones before leaving for that trip since it is likely that by the time you return most of your loved ones will no longer be alive.
ERIS
Eris Discovered in January 2005 by a team from the Palomar Observatory led by Professor Michael E. Brown. This dwarf planet has a size very similar to Pluto. So far, no space probe has visited this object, and its shape has not been directly observed. Calculations of its light curve suggest that Eris is spherical, just like Pluto. In 2005, the adaptive optics team at Hawaii’s Keck telescopes observed the presence of a satellite in orbit around Eris. Considering that at the time, the nickname “Xena” was being used to refer to this dwarf Planet, Brown’s team gave the satellite the nickname “Gabrielle,” the companion of the warrior princess. Later the International Astronomical Union (IAU) would assign it the official name of Dysnomia. Eris is so far away that it takes 557 Earth years to complete an orbit around the Sun. It is currently located almost at the maximum possible distance from the Sun (aphelion), about 95.7 astronomical units from Earth, equivalent to 8,895 million miles (14,316 million kilometers). More than double what Pluto finds. The fastest spacecraft we have would take us 40 to 50 years to reach Eris, a lifetime. A spacecraft that wanted to go back and forth from Earth to Eris would take nearly 100 years to complete that fantastic journey. By the time the spacecraft will return to Earth, likely, we have even developed 100 times faster craft. Most of the dwarf planets are located far beyond the orbit of Neptune and Pluto; in those remote regions of the solar system, there are other equally exciting bodies; one of them is the Kuiper belt, where it is believed that all long-period comets, such as the famous Halley’s Comet come from
CONCLUSION
Reaching dwarf planets in our solar system can take varying amounts of time, depending on their distance from Earth and the speed of the spacecraft. For example, NASA’s New Horizons mission traveled over 3 billion miles at an average speed of 36,000 miles per hour, taking about 9.5 years to reach Pluto. More distant dwarf planets like Eris and Haumea would necessitate even longer journeys, potentially lasting over a decade. These missions are constrained by current propulsion technology, resulting in lengthy endeavors. However, advancements in space travel could eventually shorten travel times, creating new opportunities for exploring remote celestial bodies.