Sunday, December 11, 2011

exercise

Fill in all the gaps, then press "Check" to check your answers.
   dark side      full moon      lunar      penumbra      straight line   

1. A eclipse occurs when the Earth blocks sunlight from reaching the Moon.

2. Eclipse of the Moon occurs if the Earth, the Moon and the Sun are in a and the position of the Earth is between the Sun and the Moon.

3. An eclipse of the Moon occurs only during .

4. An eclipse of the Moon can be seen with the naked eye if a person is on the of the Earth.

5. The shadow of the Earth has two regions: A dark shadow region (umbra) and a light shadow region ( ).

Lunar Eclipse

eclipse of the Moon

A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes. The most recent total lunar eclipse occurred on December 10, 2011. The previous total lunar eclipse occurred on June 15, 2011; The recent eclipse was visible from all of Asia and Australia, seen as rising over Europe and setting over Northwest North America. The last to previous total lunar eclipse occurred on December 21, 2010, at 08:17 UTC.[1]
Unlike a solar eclipse, which can only be viewed from a certain relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours, whereas a total solar eclipse lasts for only a few minutes at any given place, due to the smaller size of the moon's shadow. Also unlike solar eclipses, lunar eclipses are safe to view without any eye protection or special precautions, as they are no brighter (indeed dimmer) than the full moon itself.

food chain and food web

What is the difference between the 'Food Chain' and 'Food Web?'
A popular misnomer, the 'food chain' is not actually a linear chain but a complex web.  Energy is passed from one organism to another in a complex network like a spider's web.
The food chain consists of four main parts:
  • The Sun, which provides the energy for everything on the planet.
  • Producers: these include all green plants.  These are also known as autotrophs, since they make their own food.  Producers are able to harness the energy of the sun to make food.  Ultimately, every (aerobic) organism is dependent on plants for oxygen (which is the waste product from photosynthesis) and food (which is produced in the form of glucose through photosynthesis).  They make up the bulk of the food chain or web.
  • Consumers: In short, consumers are every organism that eats something else.  They include herbivores (animals that eat plants), carnivores (animals that eat other animals), parasites (animals that live off of other organisms by harming it), and scavengers (animals that eat dead animal carcasses).  Primary consumers are the herbivores, and are the second largest biomass in an ecosystem.  The animals that eat the herbivores (carnivores) make up the third largest biomass, and are also known as secondary consumers.  This continues with tertiary consumers, etc.
  • Decomposers: These are mainly bacteria and fungi that convert dead matter into gases such as carbon and nitrogen to be released back into the air, soil, or water.  Fungi, and other organisms that break down dead organic matter are known as saprophytes.  Even though most of us hate those mushrooms or molds, they actually play a very important role.  Without decomposers, the earth would be covered in trash.  Decomposers are necessary since they recycle the nutrients to be used again by producers.

picture of food chain and food web


www.sciencebob.com

FOOD CHAIN
(just one path of energy)

FOOD WEB
(everything is connected!)