火山上空的大近合
A Volcanic Great Conjunction
Image Credit & Copyright: Francisco Sojuel
Explanation: Where can I see the Great Conjunction? Near where the Sun just set. Directionally, this close passing of Jupiter and Saturn will be toward the southwest. Since the planetary pair, the Sun, and the Earth are nearly in a geometric straight line, the planets will be seen to set just where the Sun had set — from every location on Earth. When can I see the Great Conjunction? Just after sunset. Since the two planets are so near the Sun directionally, they always appear in the sky near the Sun, but can best be seen when the Earth blocks the Sun but not the planets: sunset. Soon thereafter, Jupiter and Saturn will also set, so don’t be late! Is tomorrow night the only night that I can see the Great Conjunction? Tomorrow night the jovian giants will appear the closest, but on any night over the next few days they will appear unusually close. Technically, the closest pass happens on 21 December at 18:20 UTC. Will there be an erupting volcano on the horizon near the Great Conjunction? Yes, for example if you live in Guatemala where the featured image was taken. Otherwise, generally, no. In the featured image captured last week, Jupiter and Saturn are visible toward the right, just above a tree, and bathed in the diffuse glow of zodiacal light.
Growing Gallery: Notable images of the Great Conjunction submitted to APOD
Tomorrow’s picture: one day short
火山上空的大近合
影像提供与版权: Francisco Sojuel
说明: 在天空何处能见到大近合？在刚日落的那个方位。以方向来说，木星和土星会在西南方擦身而过。目前这对行星、太阳和地球几乎排成一直线，所以在地球任何地方想看这对行星，得往日落的方位找。何时能见到大近合？刚日落之后。目前这对行星和太阳几乎同方位，在天空靠得很近，只能在地球刚遮住太阳的日落后，而这对行星仍低悬在天空时，才能见到它们。不过要看得快，因为木星与土星也很快就会西沉。明晚是观赏大近合的唯一夜晚吗？明晚它们的间距最小，不过在接下来的几晚里，它们也靠得很近。精确的说，大近合发生在12月21日世界时18:20（+8时区22日02:20）。大近合时，地平线附近的火山会发生喷发吗？通常不会，除非你住瓜地马拉拍下这张照片的地点附近。在这幅摄于上星期的主题影像里，近合的木星和土星悬在右侧的树梢上方，并且沉浸在弥漫的黄道光里。
成长的画廊：提交给APOD的大近合的著名图像
明日的图片: one day short
