Earth closest to sun on January 4, 2009
Image: NASA
Sunday, January 4, 2009.
Today, the Earth is at perihelion – its closest point to the sun for this year.
Our planet swings closest to the sun today, while it’s winter in the northern hemisphere. Six months from today, in early July, the Earth will be at aphelion – its farthest point from the sun – during northern hemisphere summer. So our distance from the sun doesn’t cause Earth’s seasons.
Our average distance from the sun is 150 million kilometers – 93 million miles. But the Earth’s orbit around the sun isn’t a perfect circle. Instead, it’s an ellipse – like a squashed circle. We’re 5 million kilometers – or 3 million miles – closer to the sun today than we’ll be in early July. This variation in the Earth-sun distance doesn’t bring seasonal change, though. It’s the tilt of the Earth’s axis that gives our planet its four seasons.
Every January, Earth’s northern axis is tilted away from the sun, while the southern axis points toward the sun. Because the northern hemisphere leans away from the sun at this time of year, the daylight hours are short, and the sun shines low during the day for us.
Meanwhile, daylight hours are long and the sun climbs high into the sky for those at or south of the equator.
Jan. 04, 2009
Hi Happy New Year,
When is the next time Haleycomet’s is due to be seem?
Jan. 04, 2009
Hi Happy New Year,
When is the next time Haley comet’s is due to be seem?
Here in Argentina (31° south) today, perihelion day, we are feeling the sun in a great way… so hot! Regards…
The comet was last seen in 1986, so it should be seen again around
2061. Aside from the fact that distance from the sun does not cause the seasons, what are some other implications of aphelion and perihelion?
Deborah,
Thank you for answering vhpronnette’s question on Halley’s Comet. Although the seasons are caused by the tilt of the Earth’s axis, the Earth’s elliptical orbit affects seasonal length. For instance, Earth is closest to the sun – at perihelion – during a northern hemisphere winter. Because the Earth travels fastest in its orbit when at perihelion, this makes winter the shortest season in the northern hemisphere (and summer the shortest season in the southern hemisphere). However, Earth reaches aphelion – its farthest distance from the sun – in early July. Because Earth travels most slowly at aphelion, this makes summer the longest season in the northern hemisphere. A northern hemisphere winter is almost 5 days shorter than a northern hemisphere summer.
Bruce
What is the evidence that the earth is moving around the sun versus the sun moving around the earth?
Anthony,
For starters, the Greek astronomer Aristarchus in the 3nd century B.C. used geometry to figure out that the sun is much larger than our planet Earth. For this reason, Aristarchus believed the smaller body (Earth) must go around the larger body (the sun). Aristarchus postulated the existance of a sun-centered solar system almost two thousand years before Copernicus did.
Finding evidence of Earthly motion was a long and painful process, demanding instruments of great precision that were not available in olden times. Proof of Earthly motion came with Bradley’s Discovery of the Aberration of Starlight and the finding of Stellar Parallax.
Bruce
i need more information. Im in 6th grade and i need help. If more was included than i would do better. This no help at all..well a little but i need a lot
- Brianna
Brianna,
Help me out and perhaps I can help you. What is your question?
Bruce
Where is our location in the universe, in relation to the center? I know our Milky Way Galaxy is 100,000 light years across, but how thick (tall, high) is it? Are most of the other stars we explore just in our own galaxy? How big is the universe? Is it expanding and contracting at the same time (due to blackholes)/ rate, and therefore at about the same size or is one more than the other at this point in time since the universe began?
David,
All the stars that you see with the unaided eye belong to our home galaxy, the Milky Way. Astronomers explore stars both within and outside our galaxy. Yes, the disk of the Milky Way is estimated to be 100,000 light-years wide. The disk is thought to be over 2,000 light-years thick, except near the galactic center, where it bulges out to 16,000 light-years. Astronmers believe the universe is expanding, due to the measurable red shift in the spectra of distant galaxies.
Forgive me if I leave the more speculative questions unanswered for the meantime.
Bruce