Screen shot from an online interactive sky chart viewer under development at A/CC to show the paths of objects that are passing Earth at less than ten lunar distances (LD). Objects in white are outside ten LD at the date and time shown, green inside ten LD, yellow inside Earth's Hill Sphere, orange inside two LD, and red inside one LD of Earth -- all from JPL SSD Horizons data.
--> See more info and more screen shots.
Today's Traffic: There are two objects known to be traveling within ten lunar distances (LD)1 of our planet today, May 16th. 2008 JL24 is departing, starting the day at 3.99 LD and finishing at 4.64 LD. 2008 HU4 is at 6.15-6.42 LD.
One object is known to be approaching in the near future. 2008 BT18 (a planned radar target) will come inside ten LD on July 11th.
There are five objects that recently flew past Earth at less than ten LD and remain of continuing interest. See their details below.
This report was refreshed at 0002 UTC.
1. Ten lunar distances: A "lunar distance" (LD) is the average distance between Earth and Moon (about 384,400 km.). Ten lunar distances has no special astronomical importance but is a useful arbitrary "bubble" within which to organize this report. An approach by a small Solar-System body starts to become interesting at less than four LD out from Earth as it encounters our planet's "Hill sphere" (distance indicated by the blue line in this illustration at about 3.9 LD). This is a region where the Earth exercises gravitational influence over passing objects and can change their orbital paths. The Moon also has a Hill sphere, outlined here as a gray circle. (The Earth and Moon are not shown to scale.)
2. Data credit: All data on this page derived from orbit solutions comes from the NASA JPL Solar System Dynamics (SSD) Group through its Horizons system. All information about optical observations comes from the IAU Minor Planet Center (MPC) and info about radar observations comes from JPL SSD. NASA, JPL, and the MPC are not associated with this page or A/CC, and responsibility for the interpretation of this information and its use here rests entirely with A/CC. Important note: Approach times presented here as to-the-minute may have unstated uncertainties of a few minutes, or many minutes or even hours for objects with old or very short observation spans. Therefore, actual encounter distances may also vary, occasionally by as much as ten lunar distances. See JPL's Close Approach Tables for nominal vs. minimum possible passage distances and times and their note about uncertainties.
3. Size estimates: Object diameters are rough approximations derived by standard formula from H, an object's "absolute magnitude" (brightness), where higher numbers represent dimmer (thus usually smaller) objects.
| 2008 HU4 - departing | |
| Approximate diameter: | 7 meters (H=28.339) |
| Closest Earth approach: | 2.46 LD at 0117 UTC on 27 April - Note: JPL reports an approach uncertainty of 3 minutes. |
| Inside Earth's Hill sphere: | 16 April until 7 May |
| Inside ten LD of Earth: | 20 March until 29 May |
| Data based on: | JPL SSD orbit solution #8 downloaded yesterday based on 45 observations spanning 14 days |
| Optical observation: | observed from 8 locations during 13.9589 days discovered at 0747 UTC on 30 April by the Catalina Sky Survey last observed at 0647 UTC on 14 May by the Spacewatch 1.8m telescope |
| Note: | risk listed |
| 2008 JL24 - departing | |
| Approximate diameter: | 4 meters (H=29.554) |
| Closest Earth approach: | 0.45 LD at 0119 UTC on 10 May |
| Inside Earth-Moon system: | 1841 UTC on 8 May until 0800 UTC on 11 May |
| Inside Earth's Hill sphere: | 4 May until yesterday |
| Inside ten LD of Earth: | 24 April until 25 May |
| Closest Moon approach: | 0.44 LD at 1014 UTC 9 May |
| Inside one LD of Moon: | 1709 UTC on 7 May until 2134 UTC on 10 May |
| Data based on: | JPL SSD orbit solution #4 downloaded yesterday based on 74 observations spanning 3 days |
| Optical observation: | observed from 10 locations during 3.3672 days discovered at 0605 UTC on 11 May by LINEAR last observed at 1453 UTC on 14 May by Faulkes Telescope South |
| Note: | risk listed |
| 2008 BT18 - approaching | |
| Approximate diameter: | 770 meters (H=18.217) |
| Closest Earth approach: | 5.87 LD at 1455 UTC on 14 July |
| Inside ten LD of Earth: | 11 to 17 July |
| Data based on: | JPL SSD orbit solution #35 downloaded 13 May based on 199 observations spanning 1955-2008 |
| Optical observation: | observed from 26 locations during 19418.6740 days discovered at 0954 UTC on 31 Jan. by LINEAR first observed at 0526 UTC on 14 March 1955 by Rob Matson via the Palomar Digitized Sky Survey last observed at 2136 UTC on 12 May by Mirasteilas Obs. |
| Note: | radar target |
These objects either departed from ten LD during the last week or were reported observed.
| 2008 HC38 - departed | |
| Approximate diameter: | 20 meters (H=26.106) |
| Closest Earth approach: | 2.18 LD at 0113 UTC on 28 April |
| Inside Earth's Hill sphere: | 27 to 29 April |
| Inside ten LD of Earth: | 24 April until 1 May |
| Closest Moon approach: | 1.33 LD at 0200 UTC 28 April |
| Data based on: | JPL SSD orbit solution #6 downloaded 9 May based on 32 observations spanning 8 days |
| Optical observation: | observed from 8 locations during 8.0249 days discovered at 0709 UTC on 30 April by LINEAR last observed at 0745 UTC on 8 May by the Spacewatch 1.8m telescope |
| Note: | risk listed |
| 2008 JQ - departed | |
| Approximate diameter: | 27 meters (H=25.484) |
| Closest Earth approach: | 6.92 LD at 1031 UTC on 29 April |
| Inside ten LD of Earth: | 25 April until 3 May |
| Data based on: | JPL SSD orbit solution #6 downloaded 13 May based on 42 observations spanning 8 days |
| Optical observation: | observed from 7 locations during 7.9563 days discovered at 0713 UTC on 2 May by LINEAR last observed at 0610 UTC on 10 May by Astronomical Research Obs. |
| Note: | risk listed |
| 2008 JL3 - departed | |
| Approximate diameter: | 29 meters (H=25.305) |
| Closest Earth approach: | 5.12 LD at 2055 UTC on 30 April |
| Inside ten LD of Earth: | 26 April until 5 May |
| Data based on: | JPL SSD orbit solution #4 downloaded 10 May based on 29 observations spanning 4 days |
| Optical observation: | observed from 7 locations during 4.0954 days discovered at 0825 UTC on 5 May by LINEAR last observed at 1042 UTC on 9 May by Tiki Obs. |
| Note: | risk listed |
| 2008 JP24 - departed | |
| Approximate diameter: | 16 meters (H=26.684) |
| Closest Earth approach: | 2.86 LD at 0138 UTC on 7 May |
| Inside Earth's Hill sphere: | 5 to 8 May |
| Inside ten LD of Earth: | 30 April until 13 May |
| Data based on: | JPL SSD orbit solution #3 downloaded 14 May based on 61 observations spanning 3 days |
| Optical observation: | observed from 8 locations during 3.0252 days discovered at 1418 UTC on 10 May by the Siding Spring Survey last observed at 1455 UTC on 13 May by Faulkes Telescope South |
| 2008 HR3 - departed | |
| Approximate diameter: | 37 meters (H=24.823) |
| Closest Earth approach: | 3.05 LD at 1615 UTC on 11 May |
| Inside Earth's Hill sphere: | 10 to 12 May |
| Inside ten LD of Earth: | 8 to 14 May |
| Data based on: | JPL SSD orbit solution #10 downloaded 10 May based on 57 observations spanning 10 days |
| Optical observation: | observed from 9 locations during 10.0003 days discovered at 0638 UTC on 29 April by the Mt. Lemmon Survey last observed at 0639 UTC on 9 May by Tiki Obs. |