What are some examples of Environmental Factors that affect the planet?
The sun, the giant fusion explosion in the sky is the sole provider of heat on this planet and science has yet to prove any other significant factor. The sun when it's active warms above the current mean, and cosmic rays produce more clouds when the sun is quiet and the magnetic field weakens. Politics, not science has been attempting to blame humans for modern climate variation, and is failing to come up with either an unprecedented rate of modern warming, or unprecedented modern temperatures to validate the notion that CO2 emissions from human activity are the primary driver of recent temperature variation. Natural warming since the Little Ice Age requires no human intervention to explain both modern warming, and recent CO2 variation from 280 - 410 ppm. None dispute the world has been warming, none dispute the lagged response to oceanic warming and CO2 outgassing.
The smallest dwarf elliptical galaxies can contain fewer stars than some_______ clusters?
As it happens, at 6' 2" I am the worlds tallest dwarf. mmalky
Do all stars in a galaxy travel at the same speed? If so, why?
Almost.This is a super important question, and one that Jan Oort asked in the 1930s. When Oort went about plotting the velocity of stars in the galaxy vs. their radial distance, he found something really surprising: stars farther away from the center of the galaxy didn’t move much faster than stars near the center. Graphically, this is the so-called “flat rotation curve” (B in the picture below).Now, this is really weird, and definitely doesn’t match the curve you’d expect from simple Newtonian gravity given the mass we can observe in the galaxy (e.g curve A). This implies one of two things:We gravely misunderstand something about gravity.There’s more mass out there - we just can’t see it.The former has led to attempts at modifications of Newtonian gravity (see: Modified Newtonian dynamics - Wikipedia ) to resolve the discrepancy between theoretical expectation and observation. It’s worth noting here that Newtonian gravity works really really really really REALLY well. And we’re pretty sure we understand it. For this reason, most scientists today favour option 2.The latter is the* justification for the existence of “dark matter” (not dark energy — they are two very different things). Why “dark”? Because we can’t see it! Our telescopes haven’t been able to detect dark matter at any wavelength - whether it be radio, gamma ray, optical, infrared, or microwave.What do we know about dark matter?The two original contenders were:WIMPS: Weakly interacting massive particles. They do not interact electromagnetically (thus explaining why we can’t see them), but they have non-zero mass and therefore affect the local gravity.MACHOS: Massive compact halo objects. These could be things like free floating black holes or perhaps lots of lone planets. However, a large search has been conducted to detect specifically such objects and they are generally agreed to have been ruled out as a possibility for dark matter.The search continues!*There are actually a very long list of reasons to believe in dark matter. Galactic rotation curves are reason #497 on that list.
What is dark matter, and how is it affecting the universe?
In astrophysics, dark matter is matter that does not emit or reflect enough electromagnetic radiation (such as light, X-rays and so on) to be detected directly, but whose presence may be inferred from its gravitational effects on visible matter. Among the observed phenomena consistent with the existence of dark matter are the rotational speeds of galaxies and orbital velocities of galaxies in clusters, gravitational lensing of background objects by galaxy clusters such as the Bullet cluster, and the temperature distribution of hot gas in galaxies and clusters of galaxies. Dark matter also plays a central role in structure formation and Big Bang nucleosynthesis, and has measurable effects on the anisotropy of the cosmic microwave background. All these lines of evidence suggest that galaxies, clusters of galaxies, and the universe as a whole contain far more matter than is directly observable, indicating that the remainder is dark.
How do scientists measure the distance of a star?
How do scientists measure how far a star or a galaxy is? and is that fool proof? For e.g if a big star is far off and a smaller star is near by and they might look similar in intensity and size to naked eyes, but do scientists really have methods to figure out their reals distances.....assume that both of those stars are moving away from us at the same velocities...
What determines when a constellation is visible to us?
Both. Distance-A constellation is a pattern that we perceive in the distribution of stars. the stars are at widely varying distances from us, so the patterns are different depending on the viewpoint of the observer.As the distances are large the stars don't appear to move in relation to each other, if you were elsewhere in the galaxy or in another one , the patterns would be different. Latitude-What you can see from Earth does depend on where you are on Earth, in the North there are constellations that are below the horizon, and vice versa. I recommend a free and open source Astronomy program called Celestia, available here; http://www.shatters.net/celestia/index.h... that enables you to explore in 3d, it is excellent, and has a forum that is frequented by expert astronomers.There is also another Earth -view based program called Stellarium available here-http://www.stellarium.org/ that will help you to understand how it all works. Good luck.