Figure 1 (IMAGE) Moscow Institute of Physics and Technology Caption Heliographic longitude (Ls) is an angle between the imaginary straight lines connecting the sun and Mars during the spring equinox (Ls = 0°) and at any given moment. The values of Ls between 0° and 90° correspond to springtime in the Northern Hemisphere, between 90-180° to summer, between 180-270° to fall, and between 270-360° to winter. The Martian orbit is much more elongated compared to the almost circular orbit of the Earth, and summer in the Northern Hemisphere corresponds to the planet's position in aphelion (the orbit point that is farthest away from the sun), while in the Southern Hemisphere, the summer corresponds to perihelion (the point in the orbit that is the closest to the sun). Thus, the 'northern' summer is much colder than the 'southern' one. Credit Space Science Council of RAS Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.