Answer to Question 1
Comets only have tails when they are close to the Sun. When they are far from the Sun, comets are extremely dark, cold, icy objects. The icy body is called the nucleus, made of various types of ices, dirt and dust. As comets get closer to the Sun in their journeys through the Solar System, they start to warm up.
As they reach an area roughly the same distance from the sun as Jupiter, the ices start to heat up and vaporize, releasing the gases and embedded dust particles that form a coma around the comet. As comets continue traveling closer to the Sun, the dust particles and other bits of debris in the coma are blown away from the sun due to the pressure of sunlight. This process forms a dust tail.
Once comets start moving away from the Sun, their activity decreases. Their tails fade and the coma disappears. They return to just the icy nucleus again. When comets' orbits eventually bring them back towards the Sun, the coma and tails begin to form again.
Answer to Question 2
C-type asteroids have albedos less than 0.06 and would look very dark to your eyes. They are probably made of carbon-rich material similar to that in carbonaceous chondrite meteorites.
S-type asteroids have albedos of 0.1 to 0.2, so they would look brighter and also redder than C-types; S-types may be composed of rocky material.
M-type asteroids are also bright but not as red as the S-types; they seem to be metal-rich and may be fragments from iron cores of differentiated asteroids.
Prostate cancer. In this example, a large mass has grown into the urinary bladder. Prostate cancer i
Small nuclear RNAs (snRNA), 100-200 bp in length, form part of the splicing mechanisms to process mR
A completed CMS-1500 (02/12) claim form.
The I-9 form.
Jostling. A form of coarse vibration that includes mobilizing joints.
How to sketch a quadratic equation that is in standard form (Question 1)