Astronomy Picture of the Day

NASA ^ | 7/3/09 | Enrique Luque Cervigón

[sig226]

Perihelion and Aphelion
Credit & Copyright: Enrique Luque Cervigón

Explanation: This year Aphelion, the point in Earth's elliptical orbit when it is farthest from the Sun, occurs tomorrow, July 4th. Of course, that doesn't affect the seasons on our fair planet. Those are determined by the tilt of Earth's axis of rotation and not Earth's distance from the Sun, so July is still winter in the south and summer in northern hemisphere. But it does mean that on July 4th the Sun will be at its smallest apparent size. This composite neatly compares two pictures of the Sun taken with the same telescope and camera on the dates of Perihelion (closest approach) and Aphelion in 2008. The image labels include Earth's distance in kilometers from the Sun on the two dates. Otherwise difficult to notice, the change in the Sun's apparent diameter between Perihelion and Aphelion is clear. The difference amounts to a little over 3 percent.

[sig226]

I don't think it's fair that the eart is so much further away when it's summer in the northern hemisphere. Obama should do something about it.

[sig226]

[cripplecreek]

Shrinkage?

[Domandred]

I was in the pool!

[immadashell]

Anybody see any sunspots?

[Conan the Librarian]

None on this day.

Just remember how angry the sun looked not 8 years ago.

[eggman]

Solar Shrinkage. We need the government to implement a new solar tax to prevent the sun from getting even smaller.

[jongaltsr]

Any time I look directly into the sun, I see spots for a couple of hours. Is that what you mean?

[GATOR NAVY]

Off topic but I hate it when people use periods instead of commas in large numbers. I’m starting to see it more and more in dates and phone numbers too. I think it’s a European thing and it annoys me to no end.