18D/Perrine-Mrkos is a large comet whose orbit features a relatively short period, low inclination, and is controlled by Jupiter's gravitational effects. NASA JPL has classified 18D/Perrine-Mrkos as a "Near Earth Asteroid" due to its orbit's proximity to Earth, but it is not considered potentially hazardous because computer simulations have not indicated any imminent likelihood of future collision.
18D/Perrine-Mrkos orbits the sun every 2,450 days (6.71 years), coming as close as 1.27 AU and reaching as far as 5.85 AU from the sun. Based on its brightness and the way it reflects light, 18D/Perrine-Mrkos is probably between 2658.000 to 5943.469 kilometers in diameter, making it the largest asteroid/dwarf planet, very roughly comparable in size to the U.S. state of Alaska.
18D/Perrine-Mrkos's orbit is 0.29 AU from Earth's orbit at its closest point. This means that there is an wide berth between this asteroid and Earth at all times.
Orbital simulations conducted by NASA JPL's CNEOS do not show any close approaches to Earth.
18D/Perrine-Mrkos's orbit is determined by observations dating back to Nov. 29, 1961. It was last officially observed on Dec. 26, 1968. The IAU Minor Planet Center records 16 observations used to determine its orbit.
The position of 18D/Perrine-Mrkos is indicated by a ◯ pink circle. Note that the object may not be in your current field of view. Use the controls below to adjust position, location, and time.