Asteroids

2101 Adonis help

Last update: 2025-09-10 00:30 UTC

Orbital Properties

Epoch

61000.0

MJD

Orbit type

Apollo

Perihelion (q)

0.442

Aphelion (Q)

3.306

Eccentricity (e)

0.764

Inclination (i)

1.3

deg

Orbit period (P)

937.0

Earth MOID

0.01151

U parameter

0.0

A₂

-30.6

10^-15au/days²

Next Earth close approach

Date

2036-02-07

Nominal distance (from Earth center)

0.0357

5340306

Maximum Brightness

13.8

mag

Risk

Object is not in risk list

Physical Properties

Absolute Magnitude (H)

18.8

mag

Diameter

500 - 1000*

Taxonomic type

Rotation period (T)

Discovery Information

Discovery Date

1936-02-12

Observatory

Uccle

ORBIT VISUALISATION TOOLS

External links

Proper elements

Epoch

Near present day

Near middle of observation arc

Orbit properties

Epoch
Semimajor Axis
Eccentricity (e)
Inclination (i)
Long. of Ascending Node (Ω)
Arg. of Perihelion (ω)
Mean Anomaly (M)
Perihelion distance
Aphelion distance
Asc. Node-Earth Sep.
Desc. Node-Earth Sep.
MOID
Orbit Period
U parameter

Value

1-sigma variation

Unit

Epoch

Value

61000.0000

1-sigma variation

Unit

MJD

Semimajor Axis

Value

1.874025

1-sigma variation

8.534E-9

Unit

Eccentricity (e)

Value

0.764127

1-sigma variation

3.983E-8

Unit

Inclination (i)

Value

1.3200

1-sigma variation

6.534E-6

Unit

Long. of Ascending Node (Ω)

Value

349.4052

1-sigma variation

0.0004

Unit

Arg. of Perihelion (ω)

Value

43.7117

1-sigma variation

0.0004

Unit

Mean Anomaly (M)

Value

24.47917

1-sigma variation

0.00001

Unit

Perihelion distance

Value

0.442031

1-sigma variation

Unit

Aphelion distance

Value

3.306019

1-sigma variation

Unit

Asc. Node-Earth Sep.

Value

-0.504726

1-sigma variation

Unit

Desc. Node-Earth Sep.

Value

0.747971

1-sigma variation

Unit

MOID

Value

0.011513

1-sigma variation

Unit

Orbit Period

Value

937.0476

1-sigma variation

Unit

U parameter

Value

0.0

1-sigma variation

Unit

A₂

Value

-30.64177

1-sigma variation

4.52199

Unit

10^-15au/days²

Covariance Matrix

	a	e	i	Ω	ω	M	A₂
a	7.28349E-17	-9.94018E-17	9.47473E-15	1.53557E-13	-1.57117E-13	-5.32469E-14	3.79959E-8
e	-9.94018E-17	1.58620E-15	-1.06020E-14	-1.54863E-13	1.65752E-13	1.18151E-13	-6.01424E-8
i	9.47473E-15	-1.06020E-14	4.26872E-11	-8.42339E-10	8.44086E-10	-7.79843E-12	4.39853E-6
Ω	1.53557E-13	-1.54863E-13	-8.42339E-10	1.49167E-7	-1.49131E-7	-8.46831E-11	9.84832E-5
ω	-1.57117E-13	1.65752E-13	8.44086E-10	-1.49131E-7	1.49169E-7	5.29749E-11	-9.93275E-5
M	-5.32469E-14	1.18151E-13	-7.79843E-12	-8.46831E-11	5.29749E-11	7.73960E-11	-3.17629E-5
A₂	3.79959E-8	-6.01424E-8	4.39853E-6	9.84832E-5	-9.93275E-5	-3.17629E-5	2.04484E1

Date of computation: 2025-09-10 00:30 UTC

Note: The ASCII file is in a format suitable for Orbfit input.

Download ASCII file:

Physical properties

Rotation Period
Quality
Amplitude
Rotation Direction
Spinvector L
Spinvector B

Rotational properties

Value

Unit

Source

Rotation Period

Value

Unit

Source

[-]

Quality

Value

Unit

Source

[-]

Amplitude

Value

Unit

mag

Source

[-]

Rotation Direction

Value

Unit

Source

[-]

Spinvector L

Value

Unit

Source

[-]

Spinvector B

Value

Unit

Source

[-]

Taxonomy
Taxonomy (all)

Taxonomy

Value

Unit

Source

Taxonomy

Value

Unit

Source

[-]

Taxonomy (all)

Value

Unit

Source

[-]

Absolute Magnitude (H)
Slope Parameter (G)

H / G

Value

Unit

Source

Absolute Magnitude (H)

Value

18.845

Unit

mag

Source

[1]

Slope Parameter (G)

Value

0.15**

Unit

mag

Source

[1]

Albedo
Diameter

Size and albedo

Value

Unit

Source

Albedo

Value

0.05 - 0.25

Unit

Source

[2]

Diameter

Value

500 - 1000*

Unit

Source

[2]

Color Index Information

Color Index Information

Value

Unit

Source

Color Index Information

Value

Unit

mag

Source

[-]

Sightings

Sightings

Value

Unit

Source

Sightings

Value

Radar R

Unit

Source

[3]

Download this part as:

Sources

No.	Name	Additional
[1]	ESA Aegis	ESA orbit determination and impact monitoring system
[2]	Estimation	Estimated from absolute magnitude
[3]	EARN	1.) Benner, L.A.M. et al. (1996) B.A.A.S. 28, 1105. 10.41. (Radar Observations of Near-Earth Asteroids 2062 Aten, 2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN) 2.) Benner, L.A.M. et al. (1997) Icarus 130, 296-312. (Radar Detection of Near-Earth Asteroids 2062 Aten, 2101 Adonis, 3103 Eger, 4544 Xanthus, and 1992 QN) 3.) Ostro, S.J. et al. (1991) Astron. J. 102, 1490-1502. (Asteroid radar astrometry)

Observational Information

Arc Length
Unobserved
Normalized RMS of residuals

Arc Information

Value

Unit

Source

Arc Length

Value

32665

Unit

Source

[1]

Unobserved

Value

Unit

Source

[1]

Normalized RMS of residuals

Value

0.651417

Unit

Source

[1]

Astrometry Summary

First Observation
Last Observation
Total Optical Observations (Discarded)

Optical

Value

Unit

Source

First Observation

Value

1936-02-12.86349

Unit

Source

[2]

Last Observation

Value

2025-07-19.844614

Unit

Source

[2]

Total Optical Observations (Discarded)

Value

181 (5)

Unit

Source

[1]

Radar Summary

First Observation
Last Observation
Delay (Discarded)
Doppler (Discarded)
Total Optical Observations (Discarded)

Radar

Value

Unit

Source

First Observation

Value

1984-07-14

Unit

Source

[3]

Last Observation

Value

1984-07-18

Unit

Source

[3]

Delay (Discarded)

Value

0 (0)

Unit

Source

[-]

Doppler (Discarded)

Value

5 (0)

Unit

Source

[1]

Total Radar Observations (Discarded)

Value

5 (0)

Unit

Source

[1]

Note: The ASCII file is in a format suitable for Orbfit input.

Sources

No.	Name	Additional
[1]	ESA Aegis	ESA orbit determination and impact monitoring system
[2]	MPC	Minor Planet Center: https://www.minorplanetcenter.net
[3]	JPL Radar Observations	Jet Propulsion Laboratory: https://ssd.jpl.nasa.gov/dat/radar_data_ast.txt

Computation parameters

As seen from:

Initial Date: *

Final Date: *

Output option:

One line per time step

Time step:*

* - these fields are required

Close Approaches for 2101 Adonis from 1950 to 2125

Body	Date in UTC	Time uncert. in min	Nominal distance in au	Min. possible distance in au	Distance uncert. in au
VENUS	1964-03-19 01:25	< 1 min	0.0396122	0.0396101	0.0000007
EARTH	1977-01-31 04:35	< 1 min	0.1448936	0.1448924	0.0000004
VENUS	1979-08-05 23:33	< 1 min	0.0498688	0.0498675	0.0000004
EARTH	1984-07-09 00:27	< 1 s	0.0447272	0.0447269	0.0000001
EARTH	2002-06-29 17:49	< 1 min	0.1610101	0.1610091	0.0000003
VENUS	2035-11-26 06:19	< 1 min	0.0342028	0.0342008	0.0000007
EARTH	2036-02-07 06:07	< 1 min	0.0356977	0.0356951	0.0000009
EARTH	2043-07-16 04:33	< 1 min	0.1492223	0.1492209	0.0000005
EARTH	2061-07-01 20:14	< 1 min	0.1242290	0.1242256	0.0000011
EARTH	2077-02-16 22:21	< 1 min	0.1760409	0.1760388	0.0000007
EARTH	2095-02-01 11:42	< 1 min	0.1535634	0.1535610	0.0000008
EARTH	2102-07-10 00:03	< 1 min	0.0195239	0.0195228	0.0000004

Download as:

Stationary Points

Ecc. an. ast.	Ecc. an. Earth	Distance in au	Classification
51.72506977	36.27942499	0.01154975	MINIMUM
306.81912988	183.23821464	0.02112302	MINIMUM
358.33557864	288.32599487	0.55244789	SADDLE
358.30399331	108.26097703	1.44731449	SADDLE
179.78063193	110.53173197	2.30057154	SADDLE
179.77453681	290.53254231	4.30000842	MAXIMUM

Download:

MOID Plots

Click on the images to zoom-in and zoom-out