Asteroids which came closer to Earth than the Moon in 2018 by time of discovery

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, based on the close approach database of the Center for Near-Earth Object Studies (CNEOS).

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. Five asteroids (2018 BD, , 2018 UA, , and ) are confirmed to have passed within this distance, and unconfirmed or confirmed but poorly observed asteroids A106fgF, A107j4q, ZB0A262, , ZGBE54F, A1080DC , ZW87F01, and ZW900BE may have also passed within this distance.

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 . passed Earth with a velocity with respect to Earth of 29.6 km/s and was approaching the Sun at 35.9 km/s.

The CNEOS database of close approaches lists some close approaches a full orbit or more before the discovery of the object, derived by orbit calculation. The list below only includes close approaches that are evidenced by observations, thus the pre-discovery close approaches are only included if the object was found by precovery.

This list and relevant databases do not consider impacts as close approaches, thus this list does not include 2018 LA, an asteroid which was predicted to impact on Earth and burned up in its atmosphere, as well as several more objects that collided with Earth's atmosphere in 2018 which weren't discovered in advance, but were observed visually or recorded by sensors designed to detect detonation of nuclear devices.NASA.gov

Date ofclosestapproach Datediscovered Object Nominal geocentricdistance (AU)Distance from the center of Earth to the center of the object. See the NASA/JPL Solar System Dynamics Glossary: Geocentric. Earth has a radius of approximately 6,400 km.Nominal geocentricdistance (LD)Size (m)(approximate) (H)(abs. mag.) Closerapproachto Moon Refs 2018-01-02 2018-01-04 2018 AH 0.773Largest known asteroid to pass so close to Earth since in 1971. 77–170 22.7 — 2018-01-15 2018-01-17 2018 BW 0.435 6.4–14 28.1 — 2018-01-16 2018-01-17 0.341 3.3–7.5 29.5 — 2018-01-18 2018-01-18 2018 BD 0.102 2.5–5.7 30.1 — 2018-01-19 2018-01-20 0.632 17–38 26.0 — 2018-01-19 2018-01-17 2018 BC 0.734 3.5–7.8 29.4 — 2018-01-19 2018-01-18 2018 BX 0.730 4–9 29.1 — 2018-01-20 2018-01-24 0.788 6.1–14 28.2 2018-01-24 2018-01-27 0.943 12–26 26.8 — 2018-02-04 2018-02-07 0.896 6.1–14 28.2 — 2018-02-06 2018-02-07 0.253 6.7–15 28.0 — 2018-02-06 2018-02-04 2018 CC 0.492 13–28 26.6 — 2018-02-09 2018-02-08 0.182 7.3–16 27.8 — 2018-02-09 2018-02-04 2018 CB 0.181 18–39 25.9 — 2018-02-16 2018-02-10 0.924 5.1–11 28.6 — 2018-02-21 2018-02-22 2018 DQ 0.261 4–9 29.1 — 2018-02-24 2018-02-26 0.543 AU, approach range: 0.018 to 1.157 LD. There is no chance that it impacted Earth, as the minimum distance (0.018 LD) is still roughly 410 kilometers above Earth's surface. 5.2–12 28.5 ? 2018-02-25 2018-02-23 2018 DU 0.739 5.8–13 28.3 — 2018-03-02 2018-02-26 0.293 5.6–12 28.4 — 2018-03-14 2018-03-12 0.560 15–34 26.6 2018-03-17 2018-03-19 0.578 2.6–5.7 30.1 — 2018-03-18 2018-03-21 0.381 9.7–22 27.2 — 2018-03-19 2018-03-20 0.727 5.1–11 28.6 — 2018-03-23 2018-03-21 0.501 8.1–18 27.6 — 2018-03-30 2018-03-28 0.391 5.8–13 28.3 — 2018-04-07 2018-04-11 0.688 5.3–12 28.5 — 2018-04-10 2008-04-13 aka 0.783 8–18 27.6 — 2018-04-12 2018-04-11 0.781 3.3–7.5 29.5 — 2018-04-15 2018-04-14 0.502 46–100 23.8 2018-04-21 2018-04-23 0.893 18–41 25.8 — 2018-04-22 2018-04-21 2018 HV 0.403 4.4–9.9 28.9 — 2018-05-09A perigee during the asteroid's capture as temporary satellite by Earth 2020-02-15Precovery around this close approach: 2018-05-09 0.067 1.2–2.7 31.7 — 2018-05-15 2010-11-30 0.528 53–120 23.5 — 2018-05-23 2018-05-22 0.388 3.1–6.8 29.7 — 2018-05-26 2018-05-24 0.779 9.7–22 27.2 — 2018-06-15 2018-06-11 0.858 13–30 26.5 — 2018-06-16 2018-06-17 0.541 4.6–10 28.8 2018-07-07 2018-07-08 2018 NX 0.304 7.7–17 27.7 — 2018-07-08 2018-07-08 2018 NW 0.324 7.3–16 27.8 — 2018-08-10 2018-08-11 0.087 8.8–20 27.4 — 2018-08-21 2018-08-21 0.230 9.5–21 27.2 — 2018-09-03 2018-09-07 0.945 2.7–6 30.0 — 2018-09-05 2018-09-06 2018 RS 0.276 2.7–5.9 30.0 — 2018-09-06 2018-09-07 0.991 5.3–12 28.5 — 2018-09-07 2018-09-09 0.435 7.3–16 27.8 — 2018-09-08 2018-09-07 2018 RW 0.445 2–4.5 30.6 — 2018-09-09 2018-09-03 2018 RC 0.584 27–61 24.9 — 2018-09-12 2018-09-13 0.467 13–28 26.6 — 2018-09-12 2018-09-13 0.129 3–6.8 29.7 — 2018-09-15 2018-09-16 2018 SM 0.111 3.5–7.8 29.4 — 2018-09-18 2018-09-17 2018 SC 0.699 6.7–15 28.0 — 2018-09-25 2018-09-21 0.229 5.1–11 28.6 — 2018-09-30 2018-10-02 2018 TC 0.795 13–28 26.6 — 2018-10-06 2018-10-05 0.265 3.3–7.5 29.5 — 2018-10-07 2018-10-05 2018 TV 0.741 5.1–11 28.6 — 2018-10-17 2018-10-18 2018 UL 0.575 3.8–8.6 29.2 2018-10-19 2018-10-19 2018 UA 0.036 2.4–5.4 30.2 — 2018-11-02 2018-11-03 0.393 1.8–3.9 30.9 — 2018-11-05 2018-11-08 0.481 5.3–12 28.5 — 2018-11-06 2018-11-07 0.367 12–27 26.7 — 2018-11-10 2018-11-04 aka 0.992 8.4–19 27.5 — 2018-11-13 2018-11-10 0.871 8.8–20 27.4 — 2018-11-13 2018-11-16 0.653 2.5–5.7 30.1 — 2018-11-14 2018-11-15 0.517 5.1–11 28.6 2018-11-16 2018-11-17 2018 WH 0.496 2.9–6.5 29.8 — 2018-11-16 2018-11-17 2018 WG 0.080 3.7–8.2 29.3 — 2018-11-18 2018-11-17 2018 WE 0.624 5.6–12 28.4 2018-11-19 2018-11-17 2018 WJ 0.309 7–16 27.9 — 2018-11-25 2018-11-26 0.279 16–36 26.1 — 2018-11-27 2018-11-28 0.284 3.5–7.8 29.4 — 2018-11-28 2018-11-29 0.839 6.7–15 28.0 — 2018-11-30 2018-11-29 0.520 2.5–5.7 30.1 — 2018-12-02 2018-11-29 0.086 2.3–5.2 30.3 — 2018-12-11 2018-12-13 0.969 4.2–9.4 29.0 2018-12-27 2018-12-28 0.155 3.5–7.8 29.4 — 2018-12-28 2018-12-29 0.510 2.9–6.5 29.8 — 2018-12-28 2019-01-03 0.430 22–50 25.4 —

In addition to the confirmed asteroids on the above list, which feature in the CNEOS close approach database, there have been well-observed unconfirmed or confirmed but poorly observed objects with a 50% or greater chance of passing within 1 LD of the Earth, which are listed separately below.

Date ofclosestapproach Datediscovered Object Nominal geocentricdistance (AU)Nominal geocentricdistance (LD)Size (m)(approximate) (H)(abs. mag.) Closerapproachto Moon Refs 2018-01-22 2018-01-22 A106fgF Potential Impact? 0.0011distance error: 0.0000107 AU, approach range: 0 to 0.0052 LD. Assuming the observations were not made in error, there was a (~9%) this asteroid hit the Earth (Impact path). However, there was no record of an impact reported, so if it did indeed impact Earth, it was likely in an uninhabited region or in the Pacific ocean. (The further west in the impact path, the larger the asteroid would be. If it hit west of Africa or in the Indian ocean, it would have been several meters across and have been recorded.) The asteroid is unconfirmed and will likely never receive a provisional designation. 2–5 30.6 — 2018-01-25 2018-01-26 ZB0A262 0.16distance error: 0.000305 AU, approach range: 0.037 to 0.27 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 2–5 30.6 — 2018-04-12 2018-04-13 ZGBE54F 0.18distance error: 0.000347 AU, approach range: 0.047 to 0.32 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 2–7 30.0 — 2018-06-17 2018-06-17 A107j4q 0.080distance error: 0.00000608 AU, approach range: 0.078 to 0.082 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 4–11 28.9 — diagram 2018-06-23 2018-06-24 A107pL2 0.20distance error: 0.000184 AU, approach range: 0.13 to 0.28 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 3–9 29.5 — 2018-07-04 2018-07-05 ZN2E090 0.51distance error: 0.000296 AU, approach range: 0.40 to 0.63 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 4–12 28.8 — 2018-08-12 2018-08-13 A1080DC 0.11distance error: 0.0000651 AU, approach range: 0.085 to 0.136 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 1–4 31.3 — 2018-10-06 2018-10-06 ZTF01Z9 0.66distance error: 0.000600 AU, approach range: 0.43 to 0.89 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 4–12 28.8 — 2018-11-01 2018-11-01 0.11distance error: 0.0000181 AU, approach range: 0.100 to 0.115 LD. 2–5 30.6 — 2018-11-11 2018-11-11 0.40 3–10 29.1 — 2018-11-15 2018-11-17 ZW84BCD 0.33distance error: 0.0000114 AU, approach range: 0.325 to 0.333 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 2–7 30.0 — 2018-11-16 2018-11-17 ZW87F01 0.23distance error: 0.000583 AU, approach range: 0.017 to 0.46 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. There is no chance of impact as the asteroid was discovered after its closest approach. 1–2 32.3 — 2018-11-28 2018-11-29 ZW900BE 0.087distance error: 0.000165 AU, approach range: 0.023 to 0.152 LD. The asteroid is unconfirmed and will likely never receive a provisional designation. 1–4 31.2 — 2018-12-30 2018-12-31 0.28 2–7 29.8 —

Warning times by size

This sub-section visualises the warning times of the close approaches listed in the table of confirmed close approaches, 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.

Absolute magnitude H ≥ 30 (smallest) (size of a person for comparison)

Absolute magnitude 30 > H ≥ 29

Absolute magnitude 29 > H ≥ 28

Absolute magnitude 28 > H ≥ 27

Absolute magnitude 27 > H ≥ 26

Absolute magnitude 26 > H ≥ 25

Absolute magnitude 25 > H (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.