Astrophyzix Space Science Network Digital Astronomical Observatory: Historical Close Approaches

This page presents a comprehensive overview of Earth’s close encounters with asteroids, combining historical flybys with discovery statistics. The top table lists notable asteroids, showing the date of closest approach, nominal geocentric distance (in kilometers, lunar distances, and astronomical units), approximate size, absolute magnitude, and official references for each object. The lower table tracks the timing of asteroid discoveries relative to their closest approach, categorizing detections by lead time—from more than a year in advance to less than 24 hours’ warning, including cases with no prior notice. By integrating historical data with discovery trends, the dashboard allows users to visualize both the frequency of close approaches over time and the effectiveness of early detection programs, providing a clear, data-driven picture of planetary defense monitoring.

Historic Close Approaches — Astrophyzix Observatory

Historic Close Approaches to Earth

MONITORING ACTIVE

Notable Asteroid Flybys
Date of Closest Approach	Nominal Geocentric Distance	Object	Size (m)	Absolute Magnitude	Reference
1932-05-15	11,220,000 km / 29.189 LD / 0.075003 AU	1862 Apollo	1500	16.1	JPL · CAD
1936-02-07	2,217,500 km / 5.769 LD / 0.014823 AU	2101 Adonis	600	18.7	JPL · CAD
1937-10-30	740,600 km / 1.927 LD / 0.004951 AU	69230 Hermes	770–1700	17.7	JPL · CAD
1989-03-22	684,000 km / 1.779 LD / 0.004572 AU	4581 Asclepius	190–420	20.7	JPL · CAD
1991-01-18	149,200 km / 0.438 LD / 0.001124 AU	1991 BA	5.1–11	28.6	JPL · CAD
2004-03-31	12,900 km / 0.0336 LD / 0.0000863 AU	2004 FU162	3.4–7.6	29.5	JPL · CAD
2025-10-30	6,599 km / 0.0172 LD / 0.0000441 AU	2025 UC11	0.41–0.93	34.06	JPL · CAD
Earth Benchmarks	6,478 km / 0.01685 LD / 0.0000433 AU	Kármán line	N/A	N/A	Nominal limit of Earth's atmosphere
Earth Benchmarks	6,378 km / 0.01659 LD / 0.0000426 AU	Equatorial radius of Earth	N/A	N/A	Nominal equatorial radius

The colored bars in the discovery statistics table provide a visual representation of how far in advance each asteroid was detected. Green shades indicate early detection, with darker green showing discoveries made more than a year in advance and progressively lighter greens for shorter lead times. Yellow represents detections within 24 hours of closest approach, while red highlights cases where no warning was received. This color-coding allows users to quickly assess the distribution of warning times across different years, illustrating both improvements in asteroid monitoring programs and the challenges of last-minute detections. Together with the sortable tables, these visual cues make it easy to explore patterns in asteroid flybys and evaluate planetary defense readiness.

Astrophyzix Close Approach Dashboard

MONITORING ACTIVE

Notable Asteroid Flybys
Date of Closest Approach	Nominal Geocentric Distance	Object	Size (m)	Absolute Magnitude	Reference
1932-05-15	11,220,000 km / 29.189 LD / 0.075003 AU	1862 Apollo	1500	16.1	JPL · CAD
1936-02-07	2,217,500 km / 5.769 LD / 0.014823 AU	2101 Adonis	600	18.7	JPL · CAD
1937-10-30	740,600 km / 1.927 LD / 0.004951 AU	69230 Hermes	770–1700	17.7	JPL · CAD
2025-10-30	6,599 km / 0.0172 LD / 0.0000441 AU	2025 UC11	0.41–0.93	34.06	JPL · CAD

DISCOVERY STATISTICS

Time of Discovery Relative to Closest Approach
Year(s)	>1 Year	>7 Weeks	>1 Week	Up to 1 Week	No Warning	Total
2000–2007	2	22	6	23	0	53
2008	8	1	0	11	0	20
2025	2	57	36	0	94	189

Legend: >1 year advance · >7 weeks advance · >1 week advance · Up to 1 week advance · <24h no="" p="" warning="">