"Black holes" is one of the most highly searched terms about our universe. There's a fascination with the idea of a region of space having a gravitational pull so strong, nothing can escape its deadly grasp, not even a sliver of light. Well, not quite. In fact, much of what we think we know about black holes turn out to be myths.
Myth 1 - All black holes are black. As the photograph below from the Event Horizon telescope demonstrated, light can be detected near a black hole's event horizon. This is the boundary between normal space and the space affected by the black hole's gravity, from which no escape is possible. Part of this light comes from the black hole's accretion disk, a flat, pancake like structure composed of dust, gas and other debris. Friction constantly moves the disk's material inward toward the event horizon. Light also comes from jet streams which propel matter outward along the disk's north and south poles.
Myth 2: All black holes are about the same size. Black holes actually come in several different sizes which are defined by their mass. Small black holes are usually the result of a relatively short and violent collapse of a star. Recent work suggests that Intermediate black holes are found in the nuclei of some active galaxies. Super massive black holes on the other hand, are found at the center of nearly every galaxy.
Dr. Dan Evans, an Astrophysicist at NASA Headquarters says, "There's a direct relationship between the beginning of super massive black holes and the beginning of their corresponding galaxy. This strongly suggests the two were born about the same time and slowly grew in size together over billions of years."
Myth 3: If you get within a few thousand miles of a black hole, its super gravity will pull you into its center. It turns out you can get surprisingly close to a black hole. If you approached a black hole with mass equal to our Sun's for example, you could get as close as tens of miles. So imagine if we replaced our sun with a black hole of the same mass. All of the planets would continue to revolve around it, at exactly the same speed and distance as they do now.
Myth 4: Once inside a black hole, nothing ever comes out. Nope. It turns out that radiation can escape from a black hole. One of Stephen Hawking's contributions was a theory that a black hole is not so dense in a quantum mechanical sense. The slow leak of what's now known as Hawking radiation would, over time, cause the black hole to simply evaporate.
The image from the Event Horizon telescope confirmed what Albert Einstein's general theory of relativity predicted over 100 years ago - that a black hole's form is that of a perfect circle. And as scientists learn even more about the properties of this gigantic cosmic mystery we call a black hole, they'll be able to puncture even more myths.
The Period Of The Solar Minimum
Intense solar activity such as sunspots and solar flares subsides during solar minimum, but that doesn't mean the sun becomes dull. Solar activity simply changes form
High up in the clear blue noontime sky, the sun appears to be much the same day-in, day-out, year after year.
But astronomers have long known that this is not true. The sun does change. Properly-filtered telescopes reveal a fiery disk often speckled with dark sunspots. Sunspots are strongly magnetized, and they crackle with solar flares-magnetic explosions that illuminate Earth with flashes of X-rays and extreme ultraviolet radiation. The sun is a seething mass of activity.
Until it's not. Every 11 years or so, sunspots fade away, bringing a period of relative calm.
This is called solar minimum and it's a regular part of the sunspot cycle.
The sun is heading toward solar minimum now. Sunspot counts were relatively high in 2014, and now they are sliding toward a low point expected in 2019-2020.
While intense activity such as sunspots and solar flares subside during solar minimum, that doesn't mean the sun becomes dull. Solar activity simply changes form.
For instance, during solar minimum we can see the development of long-lived coronal holes.
Coronal holes are vast regions in the sun's atmosphere where the sun's magnetic field opens up and allows streams of solar particles to escape the sun as the fast solar wind.
We see these holes throughout the solar cycle, but during solar minimum, they can last for a long time - six months or more. Streams of solar wind flowing from coronal holes can cause space weather effects near Earth when they hit Earth's magnetic field. These effects can include temporary disturbances of the Earth's magnetosphere, called geomagnetic storms, auroras, and disruptions to communications and navigation systems.
During solar minimum, the effects of Earth's upper atmosphere on satellites in low Earth orbit changes too.
Normally Earth's upper atmosphere is heated and puffed up by ultraviolet radiation from the sun. Satellites in low Earth orbit experience friction as they skim through the outskirts of our atmosphere. This friction creates drag, causing satellites to lose speed over time and eventually fall back to Earth. Drag is a good thing, for space junk; natural and man-made particles floating in orbit around Earth. Drag helps keep low Earth orbit clear of debris.
But during solar minimum, this natural heating mechanism subsides. Earth's upper atmosphere cools and, to some degree, can collapse. Without a normal amount of drag, space junk tends to hang around.
There are unique space weather effects that get stronger during solar minimum. For example, the number of galactic cosmic rays that reach Earth's upper atmosphere increases during solar minimum. Galactic cosmic rays are high energy particles accelerated toward the solar system by distant supernova explosions and other violent events in the galaxy.
During solar minimum, the sun's magnetic field weakens and provides less shielding from these cosmic rays. This can pose an increased threat to astronauts traveling through space.
Solar minimum brings about many changes to our sun, but less solar activity doesn't make the sun and our space environment any less interesting.
For more news about the changes ahead, stay tuned
What Lies Inside The Jupiter
For four long centuries the gas giant's vast interior has remained hidden from view. JUNO probe, launched on August 5th, changed all that.
It's really hot inside Jupiter! No one knows exactly how hot, but scientists think it could be about 43,000°F (24,000°C) near Jupiter's center, or core.
Jupiter is made up almost entirely of hydrogen and helium. On the surface of Jupiter-and on Earth-those elements are gases. However inside Jupiter, hydrogen can be a liquid, or even a kind of metal.
These changes happen because of the tremendous temperatures and pressures found at the core.
What is pressure?
Have you ever gone swimming at the deep end of a pool? Did you notice that your ears started to hurt a little bit when you were under water? The deeper you dive, the more water there is on top of you. All of that water presses on your body-and that's pressure.
The same type of pressure happens in Jupiter's core. Under low pressure, particles of hydrogen and helium, called molecules, have lots of room to bounce around. This is when hydrogen and helium are gases.
However, the weight of all this hydrogen and helium is really heavy. This weight presses down toward the planet's core, creating high pressure. The molecules run out of room to bounce around, so instead, they slow down and crowd together. This creates a liquid.
How much pressure would you find at the center of Jupiter?
Imagine if you swam to the bottom of the Pacific Ocean. You would feel more than 16,000 pounds of force pressing down on every square inch of your body. That is approximately the weight of four cars!
The pressure at the center of Jupiter is much higher. At Jupiter's core, you would feel as much as 650 million pounds of pressure pressing down on every square inch of your body. That would be like having approximately 160,000 cars stacked up in every direction all over your body!
What lies at the very center of Jupiter?
At the moment, scientists aren't 100% sure. It may be that the planet has a solid core that is bigger than Earth. But some scientists think it could be more like a thick, boiling-hot soup.
JUNO mission is designed to find answers to such remaining questions about Jupiter. The spacecraft is orbiting the giant planet, swooping in for close-up looks to get more detailed information.
Juno has already made many new discoveries about Jupiter. Scientists hope that information from Juno will help us measure Jupiter's mass and figure out whether or not the giant planet's core is solid.
Enjoying The Geminids From Above And Below
The Geminids meteor shower will be viewed from above by the Meteor camera on the International Space Station, as well as from below by sky watchers on Earth
On the night of December 13, into the morning of December 14, 2018, tune into the night sky for a dazzling display of fireballs. Thanks to the International Space Station, this sky show - the Geminids meteor shower -- will be viewed from both above and below
Sky watchers on the Earth will be sprawled flat on their backs, scanning the skies for fleeting streaks of light or meteors from small particles or meteoroids burning up as they plunge into the atmosphere. While most of those viewers won't be pondering what the shooting stars are made of, astronomers and planetary scientists will be. The Meteor camera on the space station will provide clues.
Meteor records HD video from inside the Window Observational Research Facility (WORF) - looking through thehighest optical-quality window ever installed on a human space vehicle.
This camera helps scientists identify and monitor the activity of meteors, from bolides, extremely bright meteors that typically explode in the atmosphere, to much fainter ones not visible to the naked eye. The camera is equipped with a diffraction grating, an optical component that allows incoming light to be split into selected visible wavelengths of light that are signatures of various elements (Iron, Sodium, Calcium, and Magnesium). By measuring a spectrum or chemical fingerprint from the meteor, the presence of these elements is revealed.
Meteor Science Principal Investigator Tomoko Arai of the Chiba Institute of Technology in Japan says, Our observations focus on annual meteor showers, such as Geminids and Perseids, because their meteoroids originated from known comets or asteroids, so-called meteor showers' parent bodies. The spectral information will tell us the chemical makeup of meteoroids and of their parent bodies. This can help us understand their origin and evolution.
The instrument also helps improve estimates of how much material actually enters Earth's atmosphere. Findings could help mission planners protect spacecraft and Earth from potential collisions with meteoroids.
So what parent body spawns the debris that results in the dazzling Geminids?
Many researchers hypothesize that they are related to a rocky asteroid known as 3200 Phaethon, which passes closer to the sun than any other named asteroid.Phaethon may be a rock-comet-a dormant comet that has accumulated a thick mantle of interplanetary dust grains that can slough off as the comet nears the sun. Phaethon may be an asteroid that was once rich in ice and organics like comets, originally located in the main asteroid belt, which has become active as its orbit has evolved closer to the Sun.
Another possible explanation for the Geminids source is as follows:
There is another object - Apollo asteroid 2005 UD - that seems to be dynamically related to Phaethon and has physical similarities.Some researchers believe that 2005 UD, 3200 Phaethon, and the massive amounts of debris that cause the Geminids are all products of a larger object that has broken apart.
Researchers continue to debate the cosmic drama underlying the Geminids.
Best viewing is Friday morning around 2 AM your local time, after moonset. In the suburbs you could see around 40-50 meteors per hour. Under ideal conditions you could see about 100 meteors per hour! Darker is always better when viewing meteor showers.
