If you think about the Earth during different seasons, its orientation in space and it’s geometry, then ask yourself this question:
Would a comet in orbit around the sun have seasons too?
According to NASA, yes.
“Consider what makes the seasons on Earth. The planet Earth rotates on its axis once a day. That same axis is tilted with respect to the plane formed by the Sun and the planets, called the ecliptic. The angle formed between the Earth’s axis and the ecliptic plane, results in the seasons. When the Northern Hemisphere is tilted toward the Sun, the days are longer and there is more sunlight hitting the Earth, this is summer. When it is tilted away from the Sun, there is less sunlight on the Northern Hemisphere and it is winter.
Comets have their own geometric orientation in space and hence they too have seasons. We currently do not know the orientation of Tempel 1’s axis but we will learn that when we approach and flyby the comet observing it over time as it rotates in space. Note that Tempel 1 rotates on its axis very slowly, once every 42 hours. Our animation does not show this rotation, but its there.”
“This spectacular image of comet Tempel 1 was taken 67 seconds after it obliterated Deep Impact’s impactor spacecraft. The image was taken by the high-resolution camera on the mission’s flyby craft. Scattered light from the collision saturated the camera’s detector, creating the bright splash seen here. Linear spokes of light radiate away from the impact site, while reflected sunlight illuminates most of the comet surface. The image reveals topographic features, including ridges, scalloped edges and possibly impact craters formed long ago.”
10 other facts about comets:
- Days on comets vary. One day on comet Halley varies between 2.2 to 7.4 Earth days (the time it takes for comet Halley to rotate or spin once). Comet Halley makes a complete orbit around the sun (a year in this comet’s time) in 76 Earth years.
- Short-period comets (comets that orbit the sun in less than 200 years) reside in the icy region known as the Kuiper Belt beyond the orbit of Neptune from about 30 to 55 AU. Long-period comets (comets with long, unpredictable orbits) originate in the far-off reaches of the Oort Cloud, which is five thousand to 100 thousand AUs from the sun.
- If the sun were as tall as a typical front door, Earth would be the size of a nickel, dwarf planet Pluto would be the size of a head of a pin and the largest Kuiper Belt comet (about 100 km across, which is about one twentieth the size of Pluto) would only be about the size of a grain of dust.
- Comets are cosmic snowballs of frozen gases, rock and dust.
- A comet warms up as it nears the sun and develops an atmosphere, or coma. The coma may be hundreds of thousands of kilometers in diameter.
- Comets do not have moons.
- Comets do not have rings.
- More than 20 missions have explored comets from a variety of viewpoints.
- Comets may not be able to support life themselves, but they may have brought water and organic compounds — the building blocks of life — through collisions with Earth and other bodies in our solar system.
- Comet Halley makes an appearance in the Bayeux Tapestry from the year 1066, which chronicles the overthrow of King Harold by William the Conqueror at the Battle of Hastings
Here’s a superb documentary from The Universe titled: Ride the Comet