Asked by Anonymous
That is pretty true in my case. I tend to understand concepts early on and I might review very mildly only right before tests and still do well on exams. Just the other day I had my last final exam for the semester and I have not looked at my notes since last week, and still ended with an A in the class. Some people might be envious of that quality, but it may come at a price: stress from procrastination. It’s this anxiety I sometimes get after I don’t study and even though I THINK I know the material, I am still afraid of the chance the professor will throw a curve ball at me or something. SO that is when last minute cramming may come in. Haha I know I am not the only one.
Reblogged from distant-traveller
Question: If 2 black holes get near each other, can they then gravitationally pull matter out of the other black hole & back into “normal” space?
The short answer is no.
A black hole (in the traditional sense) is defined as an object that has collapsed so that its radius is equal to, or less than, the Schwarzschild of the object.
What does this mean?
Every object has a Schwarzschild radius; this is the point at which an object’s mass is so compressed that the gravitational influence overpowers the other forces of nature and it collapses to a singularity.
Of course, not every object is massive enough to collapse to its Schwarzschild radius. The Earth’s Schwarzschild radius, for example, is about the diameter of a small marble. If you were to apply enough energy to the Earth and compress its mass to that size, it would collapse to form a black hole. The same is true for humans, except I’d need to compress you to a point some 10-million times smaller than a marble in order to turn you into a black hole.
So, what is special about the Schwarzschild radius? This is the point at which the escape velocity for the object is equal to the speed of light. Obviously, since you can’t travel ,or faster than, the speed of light you can’t get out of a black hole neither can another black hole pull you out.
It’s important to realize that, outside of the Schwarzschild radius (also known as the event horizon), spacetime is normal. You can interact with a black hole in the same ways you interact with any other object of mass.
Image credit: NASA/CXC/A.Hobart
The combination of Titan’s low gravity and thick atmosphere would allow a human to fly by strapping “fake wings” to their arms.
The second-largest moon in the solar system, Saturn’s Titan is the only moon with a substantial atmosphere, which is much deeper than Earth’s. It’s so thick and the gravity so weak, in fact, that you could strap wings on your arms and flap them like a bird to fly. The air is mostly nitrogen, but the rest is mostly hydrocarbons, giving Titan’s atmosphere a thick orange smoggy haze that is opaque to visible light. Cassini studies Titan in infrared light (which can penetrate the haze) and with radar — and in 2004, via the Huygens Probe, an atmosphere probe became the first spacecraft to transmit from the surface of a moon other than our own. Titan is remarkably earthlike, apart from being so cold that water is as hard as rock; in addition to the atmosphere, it is the only place other than Earth known to have bodies of liquid on the surface — lakes as large as the Great Lakes, except that it’s not water: it’s probably methane or ethane. The climate is probably similar to some of our deserts, with gigantic monsoons perhaps once a decade or more, and long droughts between. NASA scientists are working on a mission called Titan Mare Explorer (TiME) specifically to study the lakes of Titan.
Read the full text here: http://mentalfloss.com/ It’s Raining on Titan! Illustration Credit & Copyright: David A. Hardy (AstroArt)
Palestinian children visiting the Marah Land Zoo outside Gaza City look at a donkey painted in a zebra-like pattern,Thursday, Oct . 8, 2009. Zoo keepers have found a creative way to draw crowds to the Gaza zoo that suffered losses during the war with Israel. Zoo workers replaced 2 zebras that died of hunger during the January war with donkeys painted black and white.
GAZA CITY, Gaza Strip — Gaza City zookeepers have found a creative way of drawing crowds to their dilapidated zoo – by painting their donkeys. The Marah Land Zoo’s only two zebras died of hunger earlier this year when they were neglected during the Israel-Hamas war.
The popular animals were too expensive to replace, so the keepers decided to design a pair of donkeys with black and white patterns instead.
Ahmad Barghouti says a professional painter used French-manufactured hair coloring to make the donkeys look like zebras.
Hasan Yaseen said since his three children have never seen a real zebra, they enjoy the Gaza version.
Aside from the two ‘zebras,’ the zoo also flaunts an aging tigress, two monkeys, and a selection of birds, rabbits and cats.
Although NASA declared the metric system as its official unit system in the 1980s, conversion factors remain an issue. The Mars Climate Orbiter, meant to help relay information back to Earth, is one notable example of the unit system struggle. The orbiter was part of the Mars Surveyor ’98 program, which aimed to better understand the climate of Mars. As the spacecraft journeyed into space on September 1998, it should have entered orbit at an altitude of 140-150km above Mars, but instead went as close as 57km. This navigation error occurred because the software that controlled the rotation of the craft’s thrusters was not calibrated in SI units. The spacecraft expected newtons, while the computer, which was inadequately tested, worked in pound forces; one pound force is equal to about 4.45 newtons. Unfortunately, friction and other atmospheric forces destroyed the Mars Climate Orbiter. The project cost $327.6 million in total. Tom Gavin, an administrator for NASA’s Jet Propulsion Laboratory in Pasadena, stated, “This is an end-to-end process problem. A single error like this should not have caused the loss of Climate Orbiter. Something went wrong in our system processes in checks and balances that we have that should have caught this and fixed it.”
Tokyo Disneyland’s Space Mountain roller coaster came to a sudden halt just before the end of a ride on December 5, 2003. This startling incident was due a broken axle. The axle in question fractured because it was smaller than the design’s requirement; because of the incorrect size, the gap between the bearing and the axle was over 1mm – when it should have been a mere 0.2mm (to picture this, imagine that the gap is the thickness of a dime, compared to what it’s supposed to be, the thickness of two sheets of common printer paper.) The accumulation of excess vibration and stress eventually caused it to break. Though the coaster derailed, there were no injuries. Once again, unit systems caused the accident. In September 1995, the specifications for the coaster’s axles and bearings were changed to metric units. In August 2002, however, the English unit plans prior to 1995 were used to order 44.14mm axels instead of the needed 45mm axels.
A Boeing 767 airplane flying for Air Canada on July 23, 1983 diminished its fuel supply only an hour into its flight. It was headed to Edmonton from Montreal, but it received low fuel pressure warnings in both fuel pumps at an altitude of 41,000 feet; engine failures followed soon after. Fortunately, the captain was an experienced glider pilot and the first officer knew of an unused air force base about 20 kilometers away. Together, they landed the plan on the runway, and only a few passengers sustained minor injuries. This incident was due partially to the airplane’s fuel indication system, which had been malfunctioning. Maintenance workers resorted to manual calculations in order to fuel the craft. They knew that 22,300kg of fuel was needed, and they wanted to know how much in liters should be pumped. They used 1.77 as their density ratio in performing their calculations. However, 1.77 was given in pounds per liter, not kilograms per liter. The correct number should have been 0.80 kilograms/liter; thus, their final figure accounted for less than half of the necessary fuel.
(NOTE: I am not hating on NASA for screwing up. Mistakes do happen. But think about how easier it could be to use an international unit system.)
Reblogged from ikenbot
How many rings do you see in this striking new image of the galaxy Messier 94 (NGC 4736) as seen by the infrared eyes of NASA’s Spitzer Space Telescope? While at first glance one might see a number of them, astronomers believe there is just one.
Historically, Messier 94 was considered to have two strikingly different rings: a brilliant, compact band encircling the galaxy’s core, and a faint, broad, swath of stars falling outside its main disk.
Astronomers have recently discovered that the outer ring, seen here in the deep blue glow of starlight, may actually be more of an optical illusion. Their 2009 study combined infrared Spitzer observations with ultraviolet data from NASA’s Galaxy Evolution Explorer, and ground-based surveys in visible (Sloan Digital Sky Survey) and near infrared light (Two Micron All Sky Survey). This more complete picture of Messier 94 indicates that we are really seeing two separate spiral arms that, from our perspective, take on the appearance of a single, unbroken ring.
The bright inner ring of Messier 94 is very real, however. This area is sometimes identified as a “starburst ring” because of the frenetic pace of star formation in this confined area. Starbursts like this can often be triggered by gravitational encounters with other galaxies, but in this case may instead be caused by the galaxy’s oval shape.
Tucked in between the inner starburst ring and the outer ring-like arms we find the galaxy’s disk, striated with greenish filaments of dust. While, at first glance, these dusty arcs look like a collection of rings, they actually follow tightly wound spiral arcs.
Messier 94 is about 17 million light years away, making it a distant neighbor of our own Milky Way galaxy. It was first discovered by Charles Messier’s assistant, Pierre Méchain, in 1781 and was added to his supervisor’s famous catalog two days later.
Reblogged from jtotheizzoe
We never sit here under the weight of all this air, the 5 x 10^18 kg of atmosphere that sits above everyone on Earth, and say “Gosh, that sure is heavy!”
You don’t realize just how powerful that 1 bar (~100 kPa) of pressure is until a train car is filled with steam, allowed to cool, and then implodes ohmygod did that just happen?
For more implosion goodness, check out this awesome video from Veritasium.