Groundhog Day (Pennsylvania German: Grund’sau dåk, Grundsaudaag, Grundsow Dawg, Murmeltiertag; Nova Scotia: Daks Day) is a popular tradition celebrated in the United States and Canada on 2 February. It derives from the Pennsylvania Dutch superstition that if a groundhog emerging from its burrow on this day sees a shadow due to clear weather, it will retreat to its den and winter will persist for six more weeks. If it does not see its shadow because of cloudiness, spring will arrive early. Continue reading
Do you know that our Earth actually rotates on a tilted axis? Earth rotates by itself around a fixed axis called the rotational axis. At the same time, Earth also orbits around the Sun in a fixed axis called the orbital axis. The rotational axis is not actually perpendicular to the orbital axis. As the result, our Earth is tilted to a certain angle compared to its orbital axis. And the celestial equator, the imaginary line in the sky above Earth’s equator, is also tilted to a certain angle compared to Earth’s orbital axis. 
Do you know that our Earth actually rotates on a tilted axis? Earth rotates by itself around a fixed axis called the rotational axis. At the same time, Earth also orbits around the Sun in a fixed axis called the orbital axis. The rotational axis is not actually perpendicular to the orbital axis. As the result, our Earth is tilted to a certain angle compared to its orbital axis. And the celestial equator, the imaginary line in the sky above Earth’s equator, is also tilted to a certain angle compared to Earth’s orbital axis. 