List of asteroid close approaches to Earth in 2021
# List of asteroid close approaches to Earth in 2021

Below is the list of asteroids that have come close to Earth in 2021.

## 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 (0.0025696 AU (384,410 km; 238,860 mi)) from Earth in 2021.

For reference, the radius of Earth is about 0.0000426 AU (6,370 km; 3,960 mi) or 0.0166 lunar distances. Geosynchronous satellites have an orbit with semi-major axis length of 0.000282 AU (42,200 km; 26,200 mi) or 0.110 lunar distances.

The largest asteroid to pass within 1 LD of Earth in 2021 was 2021 SG with an estimated diameter of around 68 meters and an absolute magnitude of 24.0. The fastest asteroid to pass within 1 LD of Earth in 2021 was 2021 $UA_7$ that passed Earth with a velocity with respect to Earth of 27.7 km/s (62,000 mph).

Rows highlighted red indicate objects which were not discovered until after closest approach

Rows highlighted yellow indicate objects discovered less than 24 hours before closest approach

Rows highlighted green indicate objects discovered more than one week before closest approach

Rows highlighted turquoise indicate objects discovered more than 7 weeks before closest approach

Rows highlighted blue indicate objects discovered more than one year before closest approach (i.e. objects successfully cataloged on a previous orbit, rather than being detected during final approach)

| Date of closest approach | Discovery | Object | Nominal geocentric distance | Nominal geocentric distance | Approx. size (m) | (H) (abs. mag) | Closer approach to Moon |
| - | - | - | - | - | - | - | - |
| Date of closest approach | Discovery | Object | (AU) | (Lunar distance) | Approx. size (m) | (H) (abs. mag) | Closer approach to Moon |
| 2021-01-01 | 2021-01-02 G96 Mt. Lemmon Survey | 2021 AA | 0.00159 AU (238,000 km; 148,000 mi) | 0.62 | 11–24 | 27.0 | — |
| 2021-01-03 | 2021-01-03 703 Catalina Sky Survey | 2021 AH | 0.00033 AU (49,000 km; 31,000 mi) | 0.13 | 5.3–12 | 28.5 | — |
| 2021-01-04 | 2021-01-05 G96 Mt. Lemmon Survey | 2021 $AH_8$ | 0.00035 AU (52,000 km; 33,000 mi) | 0.14 | 3.2–7.2 | 29.6 | — |
| 2021-01-09 | 2021-01-08 G96 Mt. Lemmon Survey | 2021 $AS_2$ | 0.00072 AU (108,000 km; 67,000 mi) | 0.28 | 3.2–7.2 | 29.6 | — |
| 2021-01-16 | 2021-01-18 G96 Mt. Lemmon Survey | 2021 $BR_2$ | 0.00049 AU (73,000 km; 46,000 mi) | 0.19 | 1.8–4.1 | 30.8 | — |
| 2021-01-18 | 2021-01-17 G96 Mt. Lemmon Survey | 2021 BK | 0.00075 AU (112,000 km; 70,000 mi) | 0.29 | 2.3–5.2 | 30.3 | — |
| 2021-01-18 | 2021-01-17 703 Catalina Sky Survey | 2021 $BV_1$ | 0.00161 AU (241,000 km; 150,000 mi) | 0.62 | 6.6–15 | 28.0 | — |
| 2021-01-18 | 2021-01-17 G96 Mt. Lemmon Survey | 2021 BO | 0.00016 AU (24,000 km; 15,000 mi) | 0.06 | 0.68–1.5 | 33.0 | — |
| 2021-01-20 | 2021-01-18 G96 Mt. Lemmon Survey | 2021 $BO_1$ | 0.00168 AU (251,000 km; 156,000 mi) | 0.65 | 3.8–8.6 | 29.2 | — |
| 2021-01-26 | 2018-01-18 | 2018 $BA_3$ | 0.00250 AU (374,000 km; 232,000 mi) | 0.97 | 14–31 | 26.4 | — |
| 2021-02-04 | 2021-02-05 703 Catalina Sky Survey | 2021 CV | 0.00135 AU (202,000 km; 125,000 mi) | 0.52 | 4.4–9.9 | 28.9 | — |
| 2021-02-09 | 2021-02-09 I41 Palomar Mountain—ZTF | 2021 $CZ_3$ | 0.00015 AU (22,000 km; 14,000 mi) | 0.06 | 1.7–3.8 | 31.0 | — |
| 2021-02-11 | 2021-02-05 703 Catalina Sky Survey | 2021 CO | 0.00242 AU (362,000 km; 225,000 mi) | 0.94 | 23–52 | 25.3 | — |
| 2021-02-11 | 2021-02-11 703 Catalina Sky Survey | 2021 $CQ_5$ | 0.00119 AU (178,000 km; 111,000 mi) | 0.46 | 5.1–11 | 28.6 | — |
| 2021-02-12 | 2021-02-11 V00 Kitt Peak-Bok | 2021 $CC_6$ | 0.00113 AU (169,000 km; 105,000 mi) | 0.44 | 2.5–5.5 | 30.1 | — |
| 2021-02-12 | 2021-02-12 381 Tokyo-Kiso | 2021 $CC_7$ | 0.00217 AU (325,000 km; 202,000 mi) | 0.84 | 3.0–6.7 | 29.7 | — |
| 2021-02-13 | 2021-02-10 F51 Pan-STARRS 1, Haleakala | 2021 $CA_6$ | 0.00111 AU (166,000 km; 103,000 mi) | 0.43 | 5.2–12 | 28.6 | — |
| 2021-02-14 | 2021-02-12 T08 ATLAS-MLO, Mauna Loa | 2021 $CS_6$ | 0.00100 AU (150,000 km; 93,000 mi) | 0.39 | 7.3–16 | 27.8 | — |
| 2021-02-14 | 2021-02-13 K88 GINOP-KHK, Piszkesteto | 2021 $CW_7$ | 0.00019 AU (28,000 km; 18,000 mi) | 0.07 | 1.5–3.4 | 31.2 | — |
| 2021-02-18 | 2021-02-18 I41 Palomar Mountain—ZTF | 2021 $DN_1$ | 0.00226 AU (338,000 km; 210,000 mi) | 0.88 | 6.3–14 | 28.1 | — |
| 2021-02-18 | 2021-02-17 G96 Mt. Lemmon Survey | 2021 DG | 0.00111 AU (166,000 km; 103,000 mi) | 0.43 | 2.2–4.9 | 30.4 | — |
| 2021-02-21 | 2021-02-22 K88 GINOP-KHK, Piszkesteto | 2021 $DA_2$ | 0.00132 AU (197,000 km; 123,000 mi) | 0.51 | 3.9–8.7 | 29.2 | — |
| 2021-03-01 | 2021-03-02 | ZTF0KfF | 0.00187 AU (280,000 km; 174,000 mi) | 0.73 | 0.96–5.9 | 31.0 | ? |
| 2021-03-02 | 2021-03-01 K88 GINOP-KHK, Piszkesteto | 2021 EA | 0.00063 AU (94,000 km; 59,000 mi) | 0.24 | 6.3–14 | 28.1 | — |
| 2021-03-07 | 2021-03-06 | C4YK182 | 0.000632 AU (94,500 km; 58,700 mi) | 0.25 | 1.8–5.9 | 30.3 | — |
| 2021-03-08 | 2021-03-06 G96 Mt. Lemmon Survey | 2021 $EF_1$ | 0.00187 AU (280,000 km; 174,000 mi) | 0.73 | 3.1–6.8 | 29.7 | ✓ |
| 2021-03-09 | 2021-03-10 G96 Mt. Lemmon Survey | 2021 $EG_3$ | 0.00098 AU (147,000 km; 91,000 mi) | 0.38 | 3.8–8.6 | 29.2 | — |
| 2021-03-10 | 2021-03-11 | ScKo07a | 0.0013 AU (190,000 km; 120,000 mi) | 0.51 | 0.97–5.9 | 31.0 | — |
| 2021-03-15 | 2021-03-15 T08 ATLAS-MLO, Mauna Loa | 2021 $EN_4$ | 0.00047 AU (70,000 km; 44,000 mi) | 0.18 | 3.1–6.9 | 29.7 | — |
| 2021-03-15 | 2021-03-15 381 Tokyo-Kiso | 2021 $EP_4$ | 0.00248 AU (371,000 km; 231,000 mi) | 0.97 | 3.7–8.4 | 29.3 | — |
| 2021-03-16 | 2021-03-11 G96 Mt. Lemmon Survey | 2021 $EQ_3$ | 0.00186 AU (278,000 km; 173,000 mi) | 0.72 | 16–36 | 26.1 | ✓ |
| 2021-03-20 | 2021-03-22 G96 Mt. Lemmon Survey | 2021 $FM_2$ | 0.00056 AU (84,000 km; 52,000 mi) | 0.22 | 2.5–5.7 | 30.1 | — |
| 2021-03-21 | 2021-03-22 G96 Mt. Lemmon Survey | 2021 $FF_2$ | 0.00213 AU (319,000 km; 198,000 mi) | 0.83 | 6.3–14 | 28.1 | — |
| 2021-03-23 | 2021-03-23 | B03SK22 | 0.00019 AU (28,000 km; 18,000 mi) | 0.074 | 0.38–2.4 | 33.0 | — |
| 2021-03-23 | 2021-03-20 G96 Mt. Lemmon Survey | 2021 $FO_1$ | 0.00215 AU (322,000 km; 200,000 mi) | 0.84 | 3.4–7.6 | 29.5 | — |
| 2021-03-23 | 2021-03-18 G96 Mt. Lemmon Survey | 2021 FH | 0.00157 AU (235,000 km; 146,000 mi) | 0.61 | 12–27 | 26.7 | — |
| 2021-03-23 | 2021-03-22 G96 Mt. Lemmon Survey | 2021 $FP_2$ | 0.00216 AU (323,000 km; 201,000 mi) | 0.84 | 2.5–5.6 | 30.1 | — |
| 2021-04-01 | 2021-04-01 | A10w8qG | 0.00149 AU (223,000 km; 139,000 mi) | 0.58 | 3.2–12 | 28.9 | ✓ |
| 2021-04-03 | 2021-04-04 G96 Mt. Lemmon Survey | 2021 $GE_2$ | 0.00161 AU (241,000 km; 150,000 mi) | 0.62 | 3.9–8.8 | 29.1 | — |
| 2021-04-03 | 2021-04-06 | P11ekJ0 | 0.00188 AU (281,000 km; 175,000 mi) | 0.73 | 2.9–18 | 28.6 | — |
| 2021-04-04 | 2021-04-03 G96 Mt. Lemmon Survey | 2021 GV | 0.00224 AU (335,000 km; 208,000 mi) | 0.87 | 3.8–8.6 | 29.2 | — |
| 2021-04-05 | 2021-04-03 G96 Mt. Lemmon Survey | 2021 GS | 0.00167 AU (250,000 km; 155,000 mi) | 0.65 | 4.8–11 | 28.7 | — |
| 2021-04-05 | 2021-04-05 I41 Palomar Mountain—ZTF | 2021 $GZ_7$ | 0.00126 AU (188,000 km; 117,000 mi) | 0.49 | 4.3–9.6 | 28.9 | ✓ |
| 2021-04-06 | 2021-04-07 | P11eyxx | 0.00024 AU (36,000 km; 22,000 mi) | 0.093 | 1.4–5.4 | 30.7 | — |
| 2021-04-08 | 2021-04-07 | A10wiOp | 0.00224 AU (335,000 km; 208,000 mi) | 0.87 | 2.8–17 | 28.7 | — |
| 2021-04-08 | 2021-04-08 381 Tokyo-Kiso | 2021 $GV_4$ | 0.00212 AU (317,000 km; 197,000 mi) | 0.82 | 4.3–9.6 | 29.0 | — |
| 2021-04-09 | 2021-04-11 T08 ATLAS-MLO, Mauna Loa | 2021 $GL_{16}$ | 0.00247 AU (370,000 km; 230,000 mi) | 0.96 | 15–33 | 26.3 | ✓ |
| 2021-04-10 | 2021-04-06 F51 Pan-STARRS 1, Haleakala | 2021 $GT_3$ | 0.00171 AU (256,000 km; 159,000 mi) | 0.67 | 14–32 | 26.4 | — |
| 2021-04-10 | 2021-04-10 | TMG0042 | 0.00220 AU (329,000 km; 205,000 mi) | 0.85 | 4.4–14.3 | 28.4 | — |
| 2021-04-11 | 2021-04-10 703 Catalina Sky Survey | 2021 $GQ_5$ | 0.00248 AU (371,000 km; 231,000 mi) | 0.97 | 5.3–12 | 28.5 | — |
| 2021-04-11 | 2021-04-11 | TMG0044 | 0.00126 AU (188,000 km; 117,000 mi) | 0.49 | 2.5–9.9 | 29.4 | — |
| 2021-04-11 | 2021-04-07 | P11exfR | 0.00244 AU (365,000 km; 227,000 mi) | 0.95 | 3.1–19 | 28.5 | — |
| 2021-04-11 | 2021-04-11 | TMG0045 | 0.00156 AU (233,000 km; 145,000 mi) | 0.61 | 3.7–12 | 28.8 | — |
| 2021-04-11 | 2021-04-11 381 Tokyo-Kiso | 2021 $GA_{168}$ | 0.00156 AU (233,000 km; 145,000 mi) | 0.61 | 4.6–10 | 28.8 | — |
| 2021-04-12 | 2021-04-08 G96 Mt. Lemmon Survey | 2021 GW4 | 0.00018 AU (27,000 km; 17,000 mi) | 0.07 | 3.4–7.6 | 29.5 | — |
| 2021-04-13 | 2021-04-13 I41 Palomar Mountain—ZTF | 2021 $GC_{13}$ | 0.00228 AU (341,000 km; 212,000 mi) | 0.89 | 4.0–8.9 | 29.1 | — |
| 2021-04-13 | 2021-04-13 | ZTF0KwS | 0.00105 AU (157,000 km; 98,000 mi) | 0.41 | 2.4–15 | 29.0 | ? |
| 2021-04-13 | 2021-04-11 V00 Kitt Peak-Bok | 2021 $GC_8$ | 0.00146 AU (218,000 km; 136,000 mi) | 0.57 | 2.0–4.5 | 30.6 | — |
| 2021-04-14 | 2021-04-14 381 Tokyo-Kiso | 2021 $GQ_{10}$ | 0.00116 AU (174,000 km; 108,000 mi) | 0.45 | 12–28 | 26.6 | — |
| 2021-04-14 | 2021-04-15 T08 ATLAS-MLO, Mauna Loa | 2021 $GW_{16}$ | 0.00020 AU (30,000 km; 19,000 mi) | 0.08 | 2.5–5.7 | 30.1 | — |
| 2021-04-15 | 2021-04-17 T05 ATLAS-HKO, Haleakala | 2021 $HC_1$ | 0.00155 AU (232,000 km; 144,000 mi) | 0.60 | 6.8–15 | 28.0 | ✓ |
| 2021-04-15 | 2021-04-14 W94 MAP, San Pedro de Atacama | 2021 $GF_{10}$ | 0.00077 AU (115,000 km; 72,000 mi) | 0.30 | 6.2–14 | 28.2 | — |
| 2021-04-15 | 2021-04-14 F51 Pan-STARRS 1, Haleakala | 2021 $GN_{10}$ | 0.00192 AU (287,000 km; 178,000 mi) | 0.75 | 5.6–12 | 28.4 | ✓ |
| 2021-04-16 | 2021-04-17 | ZTF0KyD | 0.00213 AU (319,000 km; 198,000 mi) | 0.83 | 3.2–20 | 28.4 | ? |
| 2021-04-17 | 2021-04-18 703 Catalina Sky Survey | 2021 $HE_1$ | 0.00153 AU (229,000 km; 142,000 mi) | 0.59 | 4.4–9.7 | 28.9 | ✓ |
| 2021-04-17 | 2021-04-14 | P11f7ua | 0.00108 AU (162,000 km; 100,000 mi) | 0.42 | 2.9–9.4 | 29.3 | — |
| 2021-04-17 | 2021-04-17 | B04SK17 | 0.00106 AU (159,000 km; 99,000 mi) | 0.41 | 3.1–30 | 28.0 | ? |
| 2021-04-19 | 2021-04-17 G96 Mt. Lemmon Survey | 2021 HN | 0.00170 AU (254,000 km; 158,000 mi) | 0.66 | 11–25 | 26.9 | — |
| 2021-04-23 | 2021-04-25 | A10wMMp | 0.000735 AU (110,000 km; 68,300 mi) | 0.29 | 2.5–16 | 28.9 | ? |
| 2021-04-24 | 2021-04-24 | ZTF0Kzz | 0.0016 AU (240,000 km; 150,000 mi) | 0.62 | 1.2–7.5 | 30.5 | ? |
| 2021-05-02 | 2021-05-02 | S514008 | 0.00079 AU (118,000 km; 73,000 mi) | 0.31 | 2.4–15 | 29.0 | ? |
| 2021-05-02 | 2021-05-03 T05 ATLAS-HKO, Haleakala | 2021 JW | 0.00173 AU (259,000 km; 161,000 mi) | 0.67 | 8.0–18 | 27.6 | — |
| 2021-05-04 | 2021-05-03 T05 ATLAS-HKO, Haleakala | 2021 JV | 0.00094 AU (141,000 km; 87,000 mi) | 0.36 | 8.6–19 | 27.4 | — |
| 2021-05-06 | 2021-05-05 G96 Mt. Lemmon Survey | 2021 $JS_1$ | 0.00074 AU (111,000 km; 69,000 mi) | 0.29 | 5.3–12 | 28.5 | — |
| 2021-05-07 | 2021-05-09 | P11gae7 | 0.00126 AU (188,000 km; 117,000 mi) | 0.49 | 3.1–19 | 28.5 | — |
| 2021-05-08 | 2021-05-07 G96 Mt. Lemmon Survey | 2021 $JQ_2$ | 0.00045 AU (67,000 km; 42,000 mi) | 0.17 | 2.6–5.9 | 30.0 | — |
| 2021-05-08 | 2021-05-09 | P11gae5 | 0.00057 AU (85,000 km; 53,000 mi) | 0.22 | 1.3–8.2 | 30.3 | — |
| 2021-05-09 | 2021-05-12 | P11ggM3 | 0.00235 AU (352,000 km; 218,000 mi) | 0.91 | 1.2–7.5 | 30.5 | — |
| 2021-05-13 | 2021-05-08 F51 Pan-STARRS 1, Haleakala | 2021 $JB_6$ | 0.00071 AU (106,000 km; 66,000 mi) | 0.27 | 4.7–10 | 28.8 | — |
| 2021-05-14 | 2021-05-14 I41 Palomar Mountain—ZTF | 2021 $JU_6$ | 0.00044 AU (66,000 km; 41,000 mi) | 0.17 | 10–23 | 27.1 | — |
| 2021-05-27 | 2021-06-01 F51 Pan-STARRS 1, Haleakala | 2021 LV | 0.00188 AU (281,000 km; 175,000 mi) | 0.73 | 6.9–15 | 27.9 | ✓ |
| 2021-05-30 | 2021-05-30 381 Tokyo-Kiso | 2021 $KO_2$ | 0.00248 AU (371,000 km; 231,000 mi) | 0.96 | 6.6–15 | 28.0 | — |
| 2021-05-30 | 2021-05-30 | TMG0049 | 0.000726 AU (108,600 km; 67,500 mi) | 0.28 | 2.2–7.1 | 29.9 | — |
| 2021-05-31 | 2021-05-30 381 Tokyo-Kiso | 2021 $KN_2$ | 0.00097 AU (145,000 km; 90,000 mi) | 0.38 | 5.0–11 | 28.6 | — |
| 2021-05-31 | 2021-05-31 381 Tokyo-Kiso | 2021 $KQ_2$ | 0.00119 AU (178,000 km; 111,000 mi) | 0.46 | 2.7–6.1 | 30.0 | — |
| 2021-05-31 | 2021-05-31 | C5Q2Z32 | 0.0000774 AU (11,580 km; 7,190 mi) | 0.030 | 0.67–4.1 | 31.8 | — |
| 2021-06-01 | 2021-05-31 G96 Mt. Lemmon Survey | 2021 $KT_2$ | 0.00195 AU (292,000 km; 181,000 mi) | 0.76 | 5.6–12 | 28.4 | — |
| 2021-06-04 | 2021-06-05 T05 ATLAS-HKO, Haleakala | 2021 $LX_1$ | 0.00107 AU (160,000 km; 99,000 mi) | 0.42 | 10–23 | 27.1 | — |
| 2021-06-12 | 2021-06-11 F51 Pan-STARRS 1, Haleakala | 2021 $LG_5$ | 0.00106 AU (159,000 km; 99,000 mi) | 0.41 | 4.8–11 | 28.7 | — |
| 2021-06-13 | 2021-06-08 G96 Mt. Lemmon Survey | 2021 $LO_2$ | 0.00148 AU (221,000 km; 138,000 mi) | 0.58 | 6.6–15 | 28.0 | — |
| 2021-06-15 | 2021-06-18 W94 MAP, San Pedro de Atacama | 2021 MU | 0.00111 AU (166,000 km; 103,000 mi) | 0.43 | 8.8–20 | 27.4 | — |
| 2021-06-17 | 2021-06-17 T05 ATLAS-HKO, Haleakala | 2021 ME | 0.00212 AU (317,000 km; 197,000 mi) | 0.82 | 4.3–9.6 | 29.0 | — |
| 2021-07-03 | 2021-07-01 F51 Pan-STARRS 1, Haleakala | 2021 NA | 0.00044 AU (66,000 km; 41,000 mi) | 0.17 | 5.2–12 | 28.6 | — |
| 2021-07-08 | 2021-07-09 F51 Pan-STARRS 1, Haleakala | 2021 $NU_3$ | 0.00120 AU (180,000 km; 112,000 mi) | 0.47 | 5.0–11 | 28.6 | — |
| 2021-07-20 | 2021-07-19 W94 MAP, San Pedro de Atacama | 2021 OV | 0.00131 AU (196,000 km; 122,000 mi) | 0.51 | 7.5–17 | 27.8 | ✓ |
| 2021-07-31 | 2021-07-30 T08 ATLAS-MLO, Mauna Loa | 2021 $OD_1$ | 0.00170 AU (254,000 km; 158,000 mi) | 0.66 | 5.9–13 | 28.3 | — |
| 2021-08-02 | 2021-08-02 I41 Palomar Mountain—ZTF | 2021 PC | 0.00110 AU (165,000 km; 102,000 mi) | 0.43 | 12–27 | 26.7 | — |
| 2021-08-02 | 2021-08-02 T08 ATLAS-MLO | 2021 $PL_{132}$ | 0.00233 AU (349,000 km; 217,000 mi) | 0.91 | 5.2–12 | 28.5 | — |
| 2021-08-05 | 2021-08-07 F51 Pan-STARRS 1, Haleakala | 2021 $PY_4$ | 0.00188 AU (281,000 km; 175,000 mi) | 0.73 | 13–29 | 26.5 | — |
| 2021-08-06 | 2021-08-08 W94 MAP, San Pedro de Atacama | 2021 $PK_4$ | 0.00160 AU (239,000 km; 149,000 mi) | 0.62 | 6.1–14 | 28.2 | — |
| 2021-08-14 | 2021-08-15 T05 ATLAS-HKO, Haleakala | 2021 $PA_{17}$ | 0.00045 AU (67,000 km; 42,000 mi) | 0.17 | 7.3–16 | 27.8 | — |
| 2021-08-27 | 2021-08-27 T05 ATLAS-HKO, Haleakala | 2021 $QD_1$ | 0.00204 AU (305,000 km; 190,000 mi) | 0.80 | 4.8–11 | 28.7 | — |
| 2021-08-28 | 2021-08-30 F51 Pan-STARRS 1, Haleakala | 2021 $QV_3$ | 0.00085 AU (127,000 km; 79,000 mi) | 0.33 | 2.4–5.3 | 30.2 | — |
| 2021-09-02 | 2021-09-03 I41 Palomar Mountain—ZTF | 2021 $RN_5$ | 0.00253 AU (378,000 km; 235,000 mi) | 0.98 | 8.1–18 | 27.6 | ✓ |
| 2021-09-06 | 2021-09-08 F51 Pan-STARRS 1, Haleakala | 2021 $RT_4$ | 0.00177 AU (265,000 km; 165,000 mi) | 0.69 | 6.2–14 | 28.2 | — |
| 2021-09-07 | 2021-09-08 F51 Pan-STARRS 1, Haleakala | 2021 $RS_{100}$ | 0.00128 AU (191,000 km; 119,000 mi) | 0.50 | 4.7–11 | 28.8 | ✓ |
| 2021-09-08 | 2021-09-07 G96 Mt. Lemmon Survey | 2021 $RS_2$ | 0.00015 AU (22,000 km; 14,000 mi) | 0.06 | 2.3–5.1 | 30.4 | — |
| 2021-09-08 | 2021-09-07 703 Catalina Sky Survey | 2021 $RP_2$ | 0.00080 AU (120,000 km; 74,000 mi) | 0.31 | 2.3–5.2 | 30.3 | ✓ |
| 2021-09-08 | 2021-09-09 K88 GINOP-KHK, Piszkesteto | 2021 $RS_5$ | 0.00092 AU (138,000 km; 86,000 mi) | 0.36 | 5.7–13 | 28.3 | — |
| 2021-09-09 | 2021-09-05 T05 ATLAS-HKO, Haleakala | 2021 $RQ_2$ | 0.00126 AU (188,000 km; 117,000 mi) | 0.49 | 3.3–7.3 | 29.5 | — |
| 2021-09-09 | 2021-09-10 703 Catalina Sky Survey | 2021 $RB_6$ | 0.00172 AU (257,000 km; 160,000 mi) | 0.67 | 6.6–15 | 28.0 | — |
| 2021-09-11 | 2021-09-10 T05 ATLAS-HKO, Haleakala | 2021 $RG_6$ | 0.00057 AU (85,000 km; 53,000 mi) | 0.22 | 4.4–9.8 | 28.9 | — |
| 2021-09-11 | 2021-09-12 T08 ATLAS-MLO, Mauna Loa | 2021 $RG_{12}$ | 0.00217 AU (325,000 km; 202,000 mi) | 0.84 | 3.9–8.7 | 29.2 | — |
| 2021-09-12 | 2021-09-08 G96 Mt. Lemmon Survey | 2021 $RR_5$ | 0.00053 AU (79,000 km; 49,000 mi) | 0.20 | 5.6–12 | 28.4 | — |
| 2021-09-16 | 2021-09-13 F51 Pan-STARRS 1, Haleakala | 2021 $RF_{16}$ | 0.00213 AU (319,000 km; 198,000 mi) | 0.83 | 4.3–9.6 | 29.0 | — |
| 2021-09-16 | 2021-09-17 I41 Palomar Mountain—ZTF | 2021 SG | 0.00164 AU (245,000 km; 152,000 mi) | 0.64 | 42–94 | 24.0 | — |
| 2021-09-17 | 2021-09-17 I41 Palomar Mountain—ZTF | 2021 SP | $9.43×10^{−5}$ AU $(1.411×10^4$ km; $8.77×10^3$ mi) | 0.04 | 3.7–8.3 | 29.3 | — |
| 2021-09-20 | 2021-09-23 F51 Pan-STARRS 1, Haleakala | 2021 SQ | 0.00184 AU (275,000 km; 171,000 mi) | 0.72 | 5.5–12 | 28.4 | ✓ |
| 2021-09-26 | 2021-09-28 F52 Pan-STARRS 2, Haleakala | 2021 $SW_1$ | 0.00182 AU (272,000 km; 169,000 mi) | 0.71 | 2.9–6.5 | 29.8 | — |
| 2021-09-27 | 2021-09-28 T05 ATLAS-HKO, Haleakala | 2021 $SQ_1$ | 0.00111 AU (166,000 km; 103,000 mi) | 0.43 | 4.6–10 | 28.8 | — |
| 2021-09-30 | 2021-10-02 G96 Mt. Lemmon Survey | 2021 TT | 0.00089 AU (133,000 km; 83,000 mi) | 0.34 | 7.2–16 | 27.8 | — |
| 2021-10-01 | 2021-10-02 F52 Pan-STARRS 2, Haleakala | 2021 TX | 0.00028 AU (42,000 km; 26,000 mi) | 0.11 | 1.5–3.5 | 31.2 | — |
| 2021-10-03 | 2021-10-03 T08 ATLAS-MLO, Mauna Loa | 2021 $TV_1$ | 0.00108 AU (162,000 km; 100,000 mi) | 0.42 | 6.5–14 | 28.1 | — |
| 2021-10-03 | 2021-10-03 G96 Mt. Lemmon Survey | 2021 $TG_1$ | 0.00196 AU (293,000 km; 182,000 mi) | 0.76 | 6.1–14 | 28.2 | — |
| 2021-10-06 | 2021-10-06 381 Tokyo-Kiso | 2021 $TQ_4$ | 0.00255 AU (381,000 km; 237,000 mi) | 0.99 | 2.8–6.2 | 29.9 | — |
| 2021-10-10 | 2021-10-03 F52 Pan-STARRS 2, Haleakala | 2021 $TT_1$ | 0.00251 AU (375,000 km; 233,000 mi) | 0.97 | 15–34 | 26.2 | ✓ |
| 2021-10-11 | 2021-10-11 T05 ATLAS-HKO, Haleakala | 2021 $TK_{11}$ | 0.00091 AU (136,000 km; 85,000 mi) | 0.35 | 4.9–11 | 28.7 | — |
| 2021-10-11 | 2021-10-11 T05 ATLAS-HKO, Haleakala | 2021 $TT_{13}$ | 0.00036 AU (54,000 km; 33,000 mi) | 0.14 | 2.9–6.5 | 29.8 | — |
| 2021-10-11 | 2021-10-13 F51 Pan-STARRS 1, Haleakala | 2021 $TH_{15}$ | 0.00211 AU (316,000 km; 196,000 mi) | 0.82 | 4.5–10 | 28.8 | ✓ |
| 2021-10-12 | 2021-10-13 G96 Mt. Lemmon Survey | 2021 $TE_{13}$ | 0.00018 AU (27,000 km; 17,000 mi) | 0.07 | 3.7–8.2 | 29.3 | — |
| 2021-10-14 | 2021-10-14 T05 ATLAS-HKO, Haleakala | 2021 $TM_{14}$ | 0.00098 AU (147,000 km; 91,000 mi) | 0.38 | 6.7–15 | 28.0 | — |
| 2021-10-16 | 2021-10-16 703 Catalina Sky Survey | 2021 UL | 0.00024 AU (36,000 km; 22,000 mi) | 0.09 | 2.3–5.2 | 30.3 | ✓ |
| 2021-10-16 | 2021-10-14 G96 Mt. Lemmon Survey | 2021 $TJ_{15}$ | 0.00257 AU (384,000 km; 239,000 mi) | 1.00 | 5.6–13 | 28.4 | — |
| 2021-10-18 | 2021-10-11 F51 Pan-STARRS 1, Haleakala | 2021 $TG_{14}$ | 0.00167 AU (250,000 km; 155,000 mi) | 0.65 | 6.0–14 | 28.2 | — |
| 2021-10-24 | 2021-10-24 K88 GINOP-KHK, Piszkesteto | 2021 UT | 0.00100 AU (150,000 km; 93,000 mi) | 0.39 | 3.6–8.1 | 29.3 | — |
| 2021-10-25 | 2021-10-26 G96 Mt. Lemmon Survey | 2021 $UO_1$ | 0.00102 AU (153,000 km; 95,000 mi) | 0.40 | 6.7–15 | 28.0 | — |
| 2021-10-25 | 2021-10-25 703 Catalina Sky Survey | 2021 UA1 | $6.30×10^{−5}$ AU $(9.42×10^3$ km; $5.86×10^3$ mi) | 0.02 | 1.2–2.6 | 31.8 | — |
| 2021-10-27 | 2021-10-28 G96 Mt. Lemmon Survey | 2021 $UA_7$ | 0.00086 AU (129,000 km; 80,000 mi) | 0.33 | 4.7–11 | 28.8 | — |
| 2021-10-27 | 2021-10-26 G96 Mt. Lemmon Survey | 2021 $UH_1$ | 0.00048 AU (72,000 km; 45,000 mi) | 0.19 | 1.3–2.8 | 31.6 | — |
| 2021-10-29 | 2021-10-30 W94 MAP, San Pedro de Atacama | 2021 $UV_5$ | 0.00077 AU (115,000 km; 72,000 mi) | 0.30 | 4.6–10 | 28.8 | — |
| 2021-10-29 | 2021-10-31 K88 GINOP-KHK, Piszkesteto | 2021 $UT_5$ | 0.00205 AU (307,000 km; 191,000 mi) | 0.80 | 5.8–13 | 28.3 | — |
| 2021-10-29 | 2021-10-29 381 Tokyo-Kiso | 2021 $UF_{12}$ | 0.00161 AU (241,000 km; 150,000 mi) | 0.63 | 3.7–8.2 | 29.3 | — |
| 2021-10-30 | 2021-10-27 G96 Mt. Lemmon Survey | 2021 $UW_1$ | 0.00256 AU (383,000 km; 238,000 mi) | 0.99 | 16–35 | 26.1 | — |
| 2021-10-30 | 2021-10-31 T08 ATLAS-MLO, Mauna Loa | 2021 $UJ_6$ | 0.00232 AU (347,000 km; 216,000 mi) | 0.90 | 6.0–13 | 28.3 | — |
| 2021-11-01 | 2021-11-02 T08 ATLAS-MLO, Mauna Loa | 2021 VH | 0.00020 AU (30,000 km; 19,000 mi) | 0.08 | 3.2–7.1 | 29.6 | — |
| 2021-11-04 | 2021-10-31 F51 Pan-STARRS 1, Haleakala | 2021 $UO_7$ | 0.00247 AU (370,000 km; 230,000 mi) | 0.96 | 3.3–7.3 | 29.6 | — |
| 2021-11-07 | 2021-11-11 G96 Mt. Lemmon Survey | 2021 $VS_{11}$ | 0.00204 AU (305,000 km; 190,000 mi) | 0.79 | 2.2–4.8 | 28.7 | — |
| 2021-11-07 | 2021-11-06 G96 Mt. Lemmon Survey | 2021 $VK_3$ | 0.00057 AU (85,000 km; 53,000 mi) | 0.22 | 2.2–4.8 | 30.5 | — |
| 2021-11-08 | 2021-11-07 T08 ATLAS-MLO, Mauna Loa | 2021 $VL_3$ | 0.00111 AU (166,000 km; 103,000 mi) | 0.43 | 5.5–12 | 28.4 | — |
| 2021-11-08 | 2021-11-07 G96 Mt. Lemmon Survey | 2021 $VN_3$ | 0.00092 AU (138,000 km; 86,000 mi) | 0.36 | 2.0–4.6 | 30.6 | — |
| 2021-11-08 | 2021-11-07 G96 Mt. Lemmon Survey | 2021 $VM_3$ | 0.00204 AU (305,000 km; 190,000 mi) | 0.79 | 2.9–6.5 | 29.8 | — |
| 2021-11-09 | 2021-11-10 G96 Mt. Lemmon Survey | 2021 $VD_8$ | 0.00083 AU (124,000 km; 77,000 mi) | 0.32 | 2.4–5.4 | 30.2 | — |
| 2021-11-09 | 2021-11-09 G96 Mt. Lemmon Survey | 2021 $VP_{11}$ | 0.00039 AU (58,000 km; 36,000 mi) | 0.15 | 1.2–2.6 | 31.8 | — |
| 2021-11-10 | 2021-11-08 F52 Pan-STARRS 2, Haleakala | 2021 $VU_4$ | 0.00072 AU (108,000 km; 67,000 mi) | 0.28 | 5.6–13 | 28.4 | — |
| 2021-11-11 | 2021-11-10 G96 Mt. Lemmon Survey | 2021 $VY_7$ | 0.00214 AU (320,000 km; 199,000 mi) | 0.83 | 3.7–8.3 | 29.3 | — |
| 2021-11-12 | 2021-11-10 G96 Mt. Lemmon Survey | 2021 $VC_7$ | 0.00124 AU (186,000 km; 115,000 mi) | 0.48 | 6.1–14 | 28.2 | — |
| 2021-11-21 | 2021-11-24 T08 ATLAS-MLO, Mauna Loa | 2021 WP | 0.00104 AU (156,000 km; 97,000 mi) | 0.41 | 6.7–15 | 28.0 | — |
| 2021-11-26 | 2021-11-27 703 Catalina Sky Survey | 2021 $WA_1$ | 0.00206 AU (308,000 km; 191,000 mi) | 0.80 | 8.2–18 | 27.5 | ✓ |
| 2021-11-28 | 2021-11-27 G96 Mt. Lemmon Survey | 2021 $WC_1$ | 0.00136 AU (203,000 km; 126,000 mi) | 0.53 | 5.4–12 | 28.5 | — |
| 2021-11-30 | 2021-12-02 G96 Mt. Lemmon Survey | 2021 XV | 0.00136 AU (203,000 km; 126,000 mi) | 0.39 | 2.6–5.8 | 30.1 | — |
| 2021-12-01 | 2021-11-29 G96 Mt. Lemmon Survey | 2021 $WF_3$ | 0.00096 AU (144,000 km; 89,000 mi) | 0.37 | 3.5–7.9 | 29.4 | — |
| 2021-12-01 | 2021-12-02 I41 Palomar Mountain—ZTF | 2021 XL | 0.00135 AU (202,000 km; 125,000 mi) | 0.53 | 4.5–10 | 28.9 | — |
| 2021-12-04 | 2021-12-02 G96 Mt. Lemmon Survey | 2021 $XF_1$ | 0.00206 AU (308,000 km; 191,000 mi) | 0.80 | 3.3–7.4 | 29.5 | — |
| 2021-12-05 | 2021-12-03 G96 Mt. Lemmon Survey | 2021 $XC_2$ | 0.00212 AU (317,000 km; 197,000 mi) | 0.82 | 3.0–6.7 | 29.8 | — |
| 2021-12-09 | 2021-12-12 G96 Mt. Lemmon Survey | 2021 $XZ_5$ | 0.00214 AU (320,000 km; 199,000 mi) | 0.83 | 5.8–13 | 28.3 | ✓ |
| 2021-12-09 | 2021-12-08 G96 Mt. Lemmon Survey | 2021 $XU_5$ | 0.00160 AU (239,000 km; 149,000 mi) | 0.62 | 3.6–8.0 | 29.4 | ✓ |
| 2021-12-10 | 2021-12-08 G96 Mt. Lemmon Survey | 2021 $XV_4$ | 0.00120 AU (180,000 km; 112,000 mi) | 0.47 | 5.2–12 | 28.6 | — |
| 2021-12-11 | 2021-12-08 G96 Mt. Lemmon Survey | 2021 $XX_4$ | 0.00251 AU (375,000 km; 233,000 mi) | 0.98 | 5.2–12 | 28.5 | — |
| 2021-12-16 | 2021-12-12 G96 Mt. Lemmon Survey | 2021 $XC_6$ | 0.00140 AU (209,000 km; 130,000 mi) | 0.54 | 6.0–13 | 28.2 | ✓ |

### 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. It shows the effectiveness of asteroid warning systems at detecting close approaches in 2021. 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 30 and greater

(size of a person for comparison)

Absolute magnitude 29-30

Absolute magnitude 28-29

Absolute magnitude 27-28

Absolute magnitude 26-27 (probable size of the Chelyabinsk meteor)

Absolute magnitude 25-26

Absolute magnitude less than 25 (largest)

* After closest approach: 1 (100.0%)
* < 24 hours before: 0 (0.0%)
* up to 7 days before: 0 (0.0%)
* > one week before: 0 (0.0%)
* > 7 weeks before: 0 (0.0%)
* > one year before: 0 (0.0%)

### Predicted close approaches

Below is the list of predicted close approaches of near-Earth asteroids larger than magnitude 27, that were predicted to occur in 2021. This relates to the effectiveness of asteroid cataloging systems at predicting close approaches in 2021. 2018 $BA_3$ (with a 9 day observation arc from January 2018) could have passed as far as 3 million km (8 LD) from Earth.

For asteroids which were observed but not predicted in advance, see the main list above.

Rows highlighted orange indicate objects which were predicted theoretically but were not observed in practice

Rows highlighted yellow indicate objects which were predicted and observed but the predicted close approach date and distance were incorrect

Rows highlighted green indicate objects which were observed with the predicted close approach distance (within +/-50%) but wrong date

Rows highlighted turquoise indicate objects which were observed with the predicted close approach date but wrong distance (out by over 50%)

Rows highlighted blue indicate objects which were observed as predicted with the correct close approach date and distance

| Object | Predicted Date of closest approach | Actual Date of closest approach | Predicted closest approach range (Lunar distance) | Actual closest approach distance (Lunar distance) | (H) (abs. mag) | Approx. Size (m) |
| - | - | - | - | - | - | - |
| 2018 $BA_3$ | 2021-01-26 ±7 days | Not observed in 2021 | 0.74–8.2 (0.97 nominal) | Not observed in 2021 | 26.4 | 14–31 |
