This object moves — fetching its current position…
Score breakdown
· 5 badges
29 pts · Uncommon
Uncommon34 pts → Rare
Potentially hazardous+12
Aten: mostly inside Earth's orbit+8
Near-Earth object+5
Tiny fragment (<1 km)+4
Catalogue designation only+0
Total score29
5 more points to reach Rare.
Badges
🌠Near-Earth object· +5
⚠️Potentially hazardous· +12
🤏Tiny fragment (<1 km)· +4
🔢Catalogue designation only
⚱️Aten: mostly inside Earth's orbit· +8
✨ Trivia
Handle with care
🛡️What 'hazardous' means. 'Potentially hazardous' is bookkeeping, not a prediction: it means the orbit passes within 0.05 AU of Earth's and the body is big enough to matter. Nothing on that list is known to be on a collision course.
☄️If it ever hit. A rock this size arriving at a typical 20 km/s would release around 1637 megatons — about 32.7 times the largest bomb ever detonated.
What it actually is
🛸Its orbit family. An Aten-class object, spending most of its time inside Earth's orbit and crossing ours from the sunward side — which makes this family wretchedly hard to spot against the daylight.
🌞Closest approach. At its nearest it comes within 0.53 AU of the Sun — inside the orbit of Venus.
🔁One lap. A single orbit around the Sun takes it about 286 days.
🥏How far it roams. Its orbit swings between 0.53 and 1.17 AU from the Sun.
Sense of scale
🧱Sense of scale. In everyday terms it is about 2.8 football pitches across.
Standing on it
🦘Don't jump. Escape velocity here is only around 0.18 m/s. A determined jump would launch you off it and into your own orbit around the Sun.
Properties
albedo
0.271
aphelion au
1.17
designation
390725
diameter km
0.293
eccentricity
0.3803
full name
390725 (2003 HB)
h mag
19.69
inclination
18.12
mean motion deg day
1.258
moid au
0.046
name
(390725) 2003 HB
number only
yes
orbit class
ATE
perihelion au
0.527
pha
yes
semi major au
0.8497
About (390725) 2003 HB
(390725) 2003 HB is an uncommon neo. It swings within 0.527 AU of the Sun at perihelion.
An Aten-class object, spending most of its time inside Earth's orbit and crossing ours from the sunward side — which makes this family wretchedly hard to spot against the daylight.
How to see it
Like any astronomical target, (390725) 2003 HB is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. Because it moves against the background stars, the live position panel on this page tracks where it is right now. The visibility panel above works out tonight's viewing window for your saved location.
Why (390725) 2003 HB is an uncommon neo
(390725) 2003 HB scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.
That score comes from 5 science badges — Near-Earth object, Potentially hazardous, Tiny fragment (<1 km), Catalogue designation only and Aten: mostly inside Earth's orbit — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.