Apohele asteroid

Apohele asteroids, or alternatively Interior-Earth Objects (IEOs) or Atira asteroids, are a class of near-Earth asteroids. They have not only their perihelion within Earth's orbit, but also their aphelion; that is, their entire orbit is within Earth's (which has a perihelion of 0.983 AU).

The first suspected Apohele was 1998 DK36, and the first confirmed was 163693 Atira in 2003. As of August 2015, there are 16 suspected Apoheles, of which eight have well-known orbits, of which five have been determined with sufficient precision to receive a permanent number (see list below); 28 more objects have aphelia smaller than Earth's aphelion (1.017 AU). The Near Earth Object Surveillance Satellite is intended to find more.

In great part because of the search methods used to look for asteroids, there are currently no known asteroids with orbits contained within Venus or Mercury's (e.g. vulcanoids).

There is no standard name for the class. The name Apohele was proposed by the discoverers of 1998 DK36, and is the Hawaiian word for orbit; it was chosen partially because of its similarity to the words aphelion (apoapsis) and helios. Other authors adopted the designation Inner Earth Objects (IEOs). Still others, following the general practice to name a new class of asteroids for the first recognized member of that class, use the designation Atira asteroids.

Apoheles do not cross Earth's orbit and are not immediate impact threats, but their orbits may be perturbed outward by a close approach to either Mercury or Venus and become Earth-crossing asteroids in the future.

List of known and suspected Apoheles as of December 2014

Name	Perihelion (AU)	Semi-major axis (AU)	Aphelion (AU)	Eccentricity	Inclination (°)	# of oppositions (Observation arc)	(H)	Diameter (m)
1998 DK36	0.40	0.69	0.98	0.42	2.0	1 (1 day)	25.0	30
163693 Atira	0.50231509	0.741063841	0.979812588	0.3221703	25.61786	9	16.3	2,300
(164294) 2004 XZ130	0.3369003	0.61761022	0.89832016	0.4545099	2.94962	4	20.4	250
(434326) 2004 JG6	0.2978413	0.63521727	0.97259326	0.5311190	18.94480	2	18.9	550
(413563) 2005 TG45	0.4277231	0.68147914	0.93523520	0.3723607	23.32897	5	17.6	1,000
2006 KZ39 (2013 JX28)	0.2619078	0.6008387	0.93976963	0.5640963	10.7634	3	20.1	330
2006 WE4	0.6411319	0.78468533	0.92823873	0.1829439	24.7678	3	18.8	600
2007 EB26	0.116	0.548	0.979	0.789	8.49	1 (6 days)	19.6	400
(418265) 2008 EA32	0.4281163	0.61594430	0.80377231	0.3049432	28.2651	3	16.5	1,500
2008 UL90	0.4306789	0.69484017	0.95900144	0.3801756	24.30965	4	18.6	650
2010 XB11	0.28811	0.61804	0.94796	0.53383	29.881	1 (43 days)	19.9	350
2012 VE46	0.45509	0.71279	0.97050	0.36154	6.667	1 (37 days)	20.3	300
2013 TQ5	0.6536	0.7739	0.8941	0.1554	16.38	1 (23 days)	19.8	380
2014 FO47	0.5486	0.7524	0.9562	0.2708	19.18	1 (9 days)	20.2	310
2015 DR215	0.3521	0.6663	0.980	0.4716	4.09	1 (29 days)	20.0	430
2015 ME131	0.644	0.805	0.965	0.199	28.88	1 (2 days)	19.6	400

See also

• List of minor planet groups
• Minor planets