About (399433) 2001 YK4
(399433) 2001 YK4 is a rare neo. It has spectral type X: and swings within 0.593 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 41 EP
(399433) 2001 YK4
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 6 badgesRare 50 pts → Epic
- Metal-rich asteroid +14
- Darker than charcoal +10
- Crosses Earth's orbit +8
- Near-Earth object +5
- Apollo: crosses Earth's orbit +4
- Catalogue designation only +0
Total score 41
9 more points to reach Epic.
Badges
- Near-Earth object · +5
- Crosses Earth's orbit · +8
- Catalogue designation only
- Apollo: crosses Earth's orbit · +4
- Darker than charcoal · +10
- 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 Apollo-class object: its orbit is wider than Earth's but crosses it. Most known Earth-crossers belong to this family.
- Closest approach. At its nearest it comes within 0.59 AU of the Sun — inside the orbit of Venus.
- One lap. A single orbit around the Sun takes it about 4.3 years.
- How far it roams. Its orbit swings between 0.59 and 4.72 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is roughly 0.2× the height of Mount Everest.
Standing on it
- Don't jump. Escape velocity here is only around 0.81 m/s. A determined jump would launch you off it and into your own orbit around the Sun.
By the numbers
- Size. Roughly 1.3 km across.
Properties
- albedo
- 0.021
- aphelion au
- 4.72
- designation
- 399433
- diameter km
- 1.339
- eccentricity
- 0.7766
- full name
- 399433 (2001 YK4)
- h mag
- 18.58
- inclination
- 4.38
- mean motion deg day
- 0.2278
- moid au
- 0.0644
- name
- (399433) 2001 YK4
- number only
- yes
- orbit class
- APO
- perihelion au
- 0.593
- semi major au
- 2.655
- spec taxonomy
- X:
- spect
- X:
How to see it
Like any astronomical target, (399433) 2001 YK4 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 (399433) 2001 YK4 is a rare neo
(399433) 2001 YK4 scores 41 points on Spacedle's rarity scale, which places it in the rare tier. Another 9 points would lift it into a rarer tier.
That score comes from 6 science badges — Near-Earth object, Crosses Earth's orbit, Catalogue designation only, Apollo: crosses Earth's orbit, Darker than charcoal 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.