The sun is shining brightly on the new year of 2013.
On Wednesday the earth reached its closest annual point to our star, a phenomenon known as perihelion. At a paltry distance of 91.4 million miles (147 million km), the sun appears about 3.4% larger from Earth at perihelion than at aphelion, when the distance between the two is greatest.
Each year in early January, the sun shines about 7 percent more intensely than it does in early July, when it reaches its aphelion distance of about 94.5 million miles (152 million km).
The Earth’s surface is warmed about 4 degrees Fahrenheit above normal at perihelion, according to Starry Night Education. While the effect is relatively minor compared to the seasonal tilting of the Earth’s axis away from the sun, it does make Northern Hemisphere winters slightly milder than Southern Hemisphere winters at equivalent latitudes.
On average, the Earth is 93 million miles (150 million km) from the sun. The relatively small difference between perihelion and aphelion means Earth’s orbit is a near perfect circle, exceeded only by Venus and Neptune within our solar system.
Mars and Mercury have very eccentric orbits by comparison. Innermost Mercury swings dramatically between a distance of about 29 million miles (46 million km) and 43 million miles (70 million km) during its 88-day year. Along with the smaller planet’s virtual lack of atmosphere, this orbital eccentricity helps to account for wide variations in Mercury’s surface temperature– ranging from -300 degrees Fahrenheit to 800 degrees Fahrenheit.
On Earth, annual dates for perihelion and aphelion align with the regularity of Earth’s annual orbit, respectively occurring in early January and early July. The next aphelion will be July 5th 2013 at 11am EST, while the next perihelion will be on January 4th 2014 at 7am EST. Make sure to mark your calendars and wear plenty of sunscreen.
Original article: http://www.space.com/14142-earth-closest-approach-sun-perihelion.html