Below is the list of asteroid close approaches to Earth in 2018.
Timeline of known close approaches less than one lunar distance from Earth
A list of known near-Earth asteroid close approaches less than 1 lunar distance () from Earth in 2018.
For reference, the radius of Earth is approximately or 0.0166 lunar distances.Geosynchronous satellites have an orbit with semi-major axis length of or 0.110 lunar distances. Eight known asteroids (2018 BD, A106fgF, 2018 LA, A107j4q, , 2018 UA, , and ) are confirmed to have passed within this distance, and poorly-observed asteroids ZB0A262, , ZGBE54F, A1080DC , ZW87F01, and ZW900BE may have also passed within this distance. While most asteroids on this list are confirmed, well-observed unconfirmed objects with a 50% or greater chance of passing within 1 LD of the Earth are included as well.
The largest asteroid to pass within 1 LD of Earth in 2018 was with an estimated diameter of around 137 meters and an absolute magnitude of 22.5. The fastest asteroid to pass within 1 LD of Earth in 2018 was that passed Earth with a velocity with respect to Earth of .
Warning Times by Size
This sub-section visualises the warning times of the close approaches listed in the above table, depending on the size of the asteroid. The sizes of the charts show the relative sizes of the asteroids to scale. For comparison, the approximate size of a person is also shown. This is based the absolute magnitude of each asteroid, an approximate measure of size based on brightness.
Abs Magnitude 30 and greater
(size of a person for comparison)
Abs Magnitude 29-30
Absolute Magnitude 28-29
Absolute Magnitude 27-28
Absolute Magnitude 26-27
Absolute Magnitude 25-26
Absolute Magnitude less than 25 (largest)
Notes
Timeline of close approaches less than one lunar distance from the Moon
The number of asteroids listed here are significantly less than those of asteroids that approach Earth for several reasons. Asteroids that approach Earth not only move faster, but are brighter and are easier to detect with modern surveys because: Asteroids that come closer to Earth are a higher priority to confirm, and only confirmed asteroids are listed with a lunocentric approach distance. Those that closely approach the Moon are frequently lost in its glare, making them harder to confirm. They are similarly hard to discover during the new moon, when the Moon is too close to the Sun to detect asteroids while they are near the Moon.
These factors severely limit the amount of Moon-approaching asteroids, to a level many times lower than the asteroids detected passing as close to Earth.
Notes
Additional examples
An example list of near-Earth asteroids that passed more than 1 lunar distance (384,400 km or 0.00256 AU) from Earth in 2018.
Statistics
Virtual Impactors
List of asteroids that are listed on the Sentry Risk Table because they have short observation arcs with poorly constrained orbits and have a chance of impacting Earth in 2018. Given a short observation arc, many different orbits fit the observed data. These objects could be millions if not billions of kilometers from Earth on the date of a low probability virtual impactor. For example, is expected to be from Earth in December 2018 around the time of the 3 virtual impactors. 2010 GZ60 was removed from the sentry table in February 2018 after further observations were found by NEOWISE, ruling out any possible impacts.
Cumulatively among the asteroids listed below, there is a roughly 1 in 98,700 chance that any of the asteroids will impact Earth in 2018. Most of this comes from asteroid 2008 US which is only ~2 meters in diameter and had a 1 in 240,000 chance of impact on 18 April 2018.
Also included are asteroids discovered before impact (specifically, 2018 LA) and exceptionally massive fireballs with either an equivalent yield of more than 1 kiloton of TNT or an estimated size of more than 3 meters.
Notes
See also
List of asteroid close approaches to Earth
List of asteroid close approaches to Earth in 2017
List of asteroid close approaches to Earth in 2019
List of bolides (asteroids and meteoroids that impacted Earth) Asteroid impact prediction
References
External links
Near-Earth object close approaches ±30 days within 5 LD (JPL) Upcoming close approaches to Earth (ESA) Table of Asteroids Next Closest Approaches to the Earth (Sormano Observatory)