If we focus on East-West areas, t wo distinctive interpretations can be defined: the side associated with more continental area, the Maximum Facing Area (MFA), and the side associated with more apparent (normal) area, the Maximum Normal Area (MNA). The MFA is sort of East-West hemisphere area division while the MNA is based on the apparent viewable area as a disk. In practice, the longitudinal location of the MFA and MNA are close, but not necessarily the same.

The MFA is normalized based of the total continental area available in the planet while the MNA is normalized to the total area of the disk (without prior knowledge of the global land area). For example, a MFA of 68% means that 68% of the land area is in one side of the planet, while a MNA of 42% means that up to 42% of the planet's disk area is covered by land at any moment. Therefore, the MNA is somewhat related to the maximum diurnal albedo of the planet as land areas are usually brighter than ocean areas, although clouds tent to minimize the effect.

Table 1 shows the North-South and East-West analysis of the land areas of Earth's past derived from our Table 1 shows the North-South and East-West analysis of the land areas of Earth's past derived from our Visible Paleo-Earth project datasets. Figure 1 shows the hemisphere of Earth with more apparent area (MNA) in the last 750 million years (the actual longitude value of this side is show in the last column of Table 1). Figure 2 shows the full analysis for current Earth, other periods and further analysis of Table 1 results are available here (some of the previous values were slightly corrected in Table 1). We are using the curves of the Normal Area (i.e. Figure 1, c) to correlate Earth's albedo with land areas, a procedure that will be important to interpret future light curves from Earth-like exoplanets



Table 1. Distribution of land areas of Earth in the last 750 million years. The global land coverage varied little within 10 to 30%, however, there where large transitions from South to North (Late Triassic, 220 Mya) and from East to West (Early Devonian, 400 Mya). Also, note the extreme clustering of over 95% of the land areas in one side of the planet (MFA) during Pangea (Middle Triassic, 240 Mya) and Rodinia (Precambrian, 750 Mya).

Age

(Mya) Age Name Land (%) Ocean (%) Land N (%) Land S (%) MFA

(%) F-lon

(°) MNA

(%) N-lon

(°) 000 Present 29 71 68 32 68 73 42 59 020 Early Miocene 30 70 68 32 68 70 44 59 035 Late Eocene 29 71 66 34 69 20 41 53 050 Early Eocene 28 72 64 36 72 29 39 50 065 Late Cretaceous (K-Pg) 26 74 61 39 77 28 39 10 090 Late Cretaceous 23 77 53 47 83 36 35 -5 105 Early Cretaceous 24 76 54 46 86 40 39 -4 120 Early Cretaceous 26 74 57 43 90 41 46 0 150 Late Jurassic 25 75 58 42 92 36 49 2 170 Middle Jurassic 26 74 57 43 94 35 52 5 200 Late Triassic 27 73 53 47 95 33 59 3 220 Late Triassic 28 72 52 48 96 37 62 5 240 Middle Triassic 27 73 42 58 98 41 58 8 260 Late Permian 26 74 39 61 94 41 59 10 280 Early Permian 25 75 39 61 93 30 57 9 300 Late Pennsylvanian 21 79 34 66 90 35 45 8 340 Middle Mississippian 20 80 25 75 86 48 40 4 370 Late Devonian 19 81 20 80 90 56 30 13 400 Early Devonian 21 79 13 87 69 74 31 -2 430 Middle Silurian 19 81 18 82 61 -162 27 160 440 Early Silurian 19 81 15 85 75 -176 32 170 450 Late Ordovician 19 81 15 85 71 -175 30 174 470 Middle Ordovician 19 81 17 83 74 -144 33 176 500 Late Cambrian 23 77 17 83 79 -139 42 179 540 Early Cambrian 27 73 20 80 80 -153 53 176 560 Late Proterozoic 28 72 21 79 78 -162 55 171 600 Late Proterozoic 30 70 25 75 80 -177 62 161 660 Precambrian 18 82 18 82 92 176 41 159 690 Precambrian 13 87 19 81 94 171 33 153 750 Precambrian 18 82 38 62 100 156 46 156







Figure 1. Earth showing the side with more continental area (MNA) in the last 750 million years.





Figure 2. Distribution of land areas of Earth today. The figures are divided in four frames, a context paleomap in an equirectangular projection with annotated percent coverage of ocean and lands areas, including how the land is divided between the northern and southern hemisphere (a), the latitudinal distribution of land areas every 15 degrees (b), the viewable land Facing Area (top curve) and Normal Area (bottom curve) as a function of longitude (c), and the longitudinal distribution of land areas every 30 degrees (d).

Our planet shows different features as it rotates along its axis, sometimes dominated by land and others by ocean. Land areas are distributed predominantly in the Northern Hemisphere (68%) relative to the Southern Hemisphere (32%) as divided by the equator. Coincidentally, the same can be say about the East-West distribution with most in the Eastern Hemisphere (68%) relative to the Western Hemisphere (32%). These hemispheres are divided by an imaginary circle crossing -20° longitude (20°W), which makes the Eastern Hemisphere center at 73° longitude (73°E). As Earth evolved through time these numbers changed dramatically.