Table 1.

The orbital semi-major axes (astronomical units), sizes and estimated bulk H and N isotopic compositions of some of the largest objects in the inner Solar System. The isotopic compositions are given as both absolute ratios and delta values (relative to SMOW (standard mean ocean water) and air for H and N, respectively) because of the differing preferred usages in the astronomical and geochemical communities.

	orbit (AU)	radius (km)	D/H × 10−4	δD(‰)	15N/14N × 10−3	δ15N (‰)
Venusa	0.72	6052	160 ± 20	∼100 000	3.66−0.62+0.95	−4−169+258
Earth [1]	1.0	6371	1.49 ± 0.03	−43 ± 20	3.68	0
Moon [2–8]	1.0	1737	1.40 to 1.85	−100 to 190	3.67 to 3.78	−2 to 27
Marsb	1.52	3390	≤1.99	≤275	3.70	7
Vesta [9–11]	2.36	263	1.31 to 1.50	−162 to −34	<3.61	<−18

^aVenusian atmosphere [12,13].

^bMartian interior [14,15].