Every new picture from Mercury reminds one why Earth is a good place to live. NASA’s robotic MESSENGER spacecraft made a close flyby early Monday morning (around 4:40 a.m. EDT), coming within about 125 miles of Mercury’s cratered surface. It’s not a nice place, 36 million miles from the Sun. For lack of an insulating atmosphere, the daytime temperature can rise above 800 deg. F., and at night, with heat dissipating into space, it can approach -300. The days are long — as long as 58 days on Earth. Since Mercury is only about three-eighths as far from the Sun as we are, it whizzes around the Sun in 88 Earth-days, so a day there is nearly as long as a year. (There’s more HERE.) MESSENGER, launched in 2004, made a flyby in January, and won’t settle into orbit around the planet until March 2011. It’s been sent on a long, looping path around the inner solar system; a longer flight uses a lot less fuel, and needs a smaller, cheaper rocket to launch it. Full details on the mission HERE. NASA points out that if you lived on Mercury — not that you’d want to — you’d be treated to some odd sights. "Due to Mercury’s rotation and highly elliptical orbit, the Sun appears to rise briefly, set, and rise again before it travels westward across the sky. At sunset, the Sun appears to set, rise again briefly, and then set again." Some of MESSENGER’s most striking images so far are HERE, and if they spot any nice lagoons or stands of aspen trees, we’ll let you know.