About (137170) 1999 HF1
(137170) 1999 HF1 is a rare neo. It has spectral type X: and swings within 0.44 AU of the Sun at perihelion.
Its orbit genuinely intersects Earth's track around the Sun. The two paths cross; only the timing keeps them apart.
Rare neo 35 EP
(137170) 1999 HF1
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 5 badgesRare 50 pts → Epic
- Metal-rich asteroid +14
- Crosses Earth's orbit +8
- Aten: mostly inside Earth's orbit +8
- Near-Earth object +5
- Catalogue designation only +0
Total score 35
15 more points to reach Epic.
Badges
- Near-Earth object · +5
- Crosses Earth's orbit · +8
- Catalogue designation only
- Aten: mostly inside Earth's orbit · +8
- Metal-rich asteroid · +14
Trivia
What makes it special
- It crosses our path. Its orbit genuinely intersects Earth's track around the Sun. The two paths cross; only the timing keeps them apart.
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 0.44 AU of the Sun — inside the orbit of Venus.
- One lap. A single orbit around the Sun takes it about 271 days.
- How far it roams. Its orbit swings between 0.44 and 1.2 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is roughly 0.5× the height of Mount Everest.
Standing on it
- Sunlight there. At closest approach the Sun beats down about 5.2 times harder than it ever does on Earth.
By the numbers
- Estimated size. Nobody has measured its size directly. Assuming it reflects light like a typical asteroid, its brightness implies something roughly 4.2 km across.
Properties
- aphelion au
- 1.2
- designation
- 137170
- eccentricity
- 0.4625
- full name
- 137170 (1999 HF1)
- h mag
- 14.66
- inclination
- 25.66
- mean motion deg day
- 1.329
- moid au
- 0.174
- name
- (137170) 1999 HF1
- number only
- yes
- orbit class
- ATE
- perihelion au
- 0.44
- rotation period h
- 2.3192
- semi major au
- 0.8191
- spec taxonomy
- X:
- spect
- X:
How to see it
Like any astronomical target, (137170) 1999 HF1 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 (137170) 1999 HF1 is a rare neo
(137170) 1999 HF1 scores 35 points on Spacedle's rarity scale, which places it in the rare tier. Another 15 points would lift it into a rarer tier.
That score comes from 5 science badges — Near-Earth object, Crosses Earth's orbit, Catalogue designation only, Aten: mostly inside Earth's orbit and Metal-rich asteroid — 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.