Today, energy is very much on our minds, as we search for ways to power our civilization and serve the needs of our citizens.
But what is energy? Where does it come from? And where do we stand within the great power streams that shape time and space?
Energy comes from a Greek word for activity or working. In physics, it is simply the property or the state of anything in our universe that allows it to do work. Whether it is thermal, kinetic, electro-magnetic, chemical, or gravitational.
The 19th century German scientist Hermann von Helmholtz found that all forms of energy are equivalent, that one form can be transformed into any other. The laws of physics say that in a closed system – such as our universe – energy is conserved. It may be converted, concentrated, or dissipated, but it is never lost.
James Prescott Joule built an apparatus that demonstrated this principle. It had a weight that descended into water and caused a paddle to rotate. He showed that the gravitational energy lost by the weight is equivalent to heat gained by the water from friction with the paddle.
The NASA/ESA Hubble Space Telescope is working on three of the most ambitious projects in its history just now. These multicycle treasury programs are using Hubble’s unique ability to observe across the spectrum from ultraviolet, through visible, to infrared light, to build up a library of data which will serve astronomers for many years.
After circling the Earth for over two decades, Hubble has been responsible for many fascinating scientific discoveries. After the visit by astronauts in 2009 to service the spacecraft and to install new instruments, the telescope is now at the height of its powers.
As the observatory has matured, attention has turned to some ambitious projects on a scale that would not have even been considered a few years ago. Between them, these projects could help answer some of the biggest questions in astronomy today, and will contribute to science for many years to come.
Now, observing time on Hubble is a very precious commodity and it’s hugely sought after. That means that when astronomers want to use Hubble, they have to apply for observing time. And in their application, they have to be very detailed about what it is exactly they want to study, and how they’re going Continue reading Hubble Targeting the Big Questions→
Did Mars long ago develop far enough for life to arise? If so, does anything still live within Mars’ dusty plains, beneath its ice caps, or somewhere underground?
In 1964 the Mariner Four spacecraft flew by Mars and got a good look. What it saw looked more like the Moon than the Earth. Then, in the mid-1970’s, two lander-orbiter robot teams, named Viking, went in for an even closer look. The landers tested the soil for the chemical residues of life. All the evidence from Viking told us: Mars is dead. And extremely harsh.
The mission recorded Martian surface temperatures from -17 degrees Celsius down to -107. We now know it can get even colder than that at the poles. The atmosphere is 95% carbon dioxide, with only traces of oxygen. And it’s extremely thin, with less than one percent the surface pressure of Earth’s atmosphere.
And it’s bone dry. In fact, the Sahara Desert is a rainforest compared to Mars, where water vapor is a trace gas in the atmosphere. On Earth, impact craters erode over time from wind and water… and even volcanic activity. On Mars, they can linger for billions of years.
From NASA JPL marking the passage of the twin Voyager spacecraft beyond our solar system. We knew we were on a journey of discovery when we launched the Voyager spacecraft, but we had no idea how much there was to discover.
We had a sense that we knew what it felt like to be Magellan or Columbus.
Time after time we were surprised by seeing things that we had not expected or even imagined. From volcanoes erupting from the moon Io to the possibility of a liquid water ocean under the icy crust of Europa. Titan, where we found an atmosphere. Uranus’ small moon Miranda, which had one of the most complex geologic surfaces we’d seen. Even at Neptune, Triton, 40 degrees above absolute zero, even there there were geysers erupting.
It’s the only spacecraft that’s gone by Uranus. It’s the only spacecraft that’s gone by Neptune. Everything we know about those planets we know from Voyager.
To see those first pictures coming in from the outer solar system, for the first time what had been a point of light in the sky was a place.
“The dust cloud around Scheila could be 10,000 times as massive as the one ejected from comet 9P/Tempel 1 during NASA’s UMD-led Deep Impact mission,” said co-author Michael Kelley, also at the University of Maryland. “Collisions allow us to peek inside comets and asteroids. Ejecta kicked up by Deep Impact contained lots of ice, and the absence of ice in Scheila’s interior shows that it’s entirely unlike comets.”
From NASA Astrophysics and the amazings at Goddard Space Flight Center. The famous Crab Nebula supernova remnant has erupted in an enormous flare five times more powerful than any flare previously seen from the object. On April 12, NASA’s Fermi Gamma-ray Space Telescope first detected the outburst, which lasted six days.
The nebula is the wreckage of an exploded star that emitted light which reached Earth in the year 1054. It is located 6,500 light-years away in the constellation Taurus. At the heart of an expanding gas cloud lies what is left of the original star’s core, a superdense neutron star that spins 30 times a second. With each rotation, the star swings intense beams of radiation toward Earth, creating the pulsed emission characteristic of spinning neutron stars (also known as pulsars).
Apart from these pulses, astrophysicists believed the Crab Nebula was a virtually constant source of high-energy radiation. But in January, scientists associated with several orbiting observatories, including NASA’s Fermi, Swift and Rossi X-ray Timing Explorer, reported long-term brightness changes at X-ray energies.
An intimate tour of Earth’s most impressive landscapes… as captured by astronauts with their digital cameras. Dr. Justin Wilkinson from NASA’s astronaut team describes the special places that spacemen focus on whenever they get a moment.
We start with the coast of Namibia in southwestern Africa, the very dry desert coast of the Namib Desert. You can see a cloud band butting up against the shore and some straight sand dunes in the lower left of the picture. Yeah those are big red sand dunes that the astronauts say is one of the most beautiful sites that you can get when you’re flying.
Coming into the view on the left is an impact crater right in the middle of the picture, right about now and some wind streaks. We know where this area is because it’s a bit unique. We’ve got a major dune field coming into the picture on the left there: the Oriental Sand Sea, as it’s called in French, and on the top is the Isawan Sand Sea.
NASA video narrated by William Shatner, the HD 720p version. An idea born in unsettled times becomes a feat of engineering excellence, the most complex machine ever built, to bring humans to and from space and eventually construct the next stop on the road to space exploration.
From NASA Goddard Space Flight Center. Scientists have spotted the iconic surfer’s wave rolling through the atmosphere of the sun. This makes for more than just a nice photo-op: the waves hold clues as to how energy moves through that atmosphere, known as the corona.
Since scientists know how these kinds of waves — initiated by a Kelvin-Helmholtz instability if you’re being technical — disperse energy in the water, they can use this information to better understand the corona. This in turn, may help solve an enduring mystery of why the corona is thousands of times hotter than originally expected.
Kelvin-Helmholtz instabilities occur when two fluids of different densities or different speeds flow by each other. In the case of ocean waves, that’s the dense water and the lighter air. As they flow past each other, slight ripples can be quickly amplified into the giant waves loved by surfers. In the case of the solar atmosphere, which is made of a very hot and electrically charged gas called plasma, the two flows come from an expanse of plasma erupting off the sun’s surface as it passes by plasma that is not erupting. The difference in flow speeds and densities across this boundary Continue reading Catching Solar Waves→
A gem from NASA Heliophysics and the Science Visualization Studio. The sun’s magnetic field spins opposite directions on the north and south poles. These oppositely pointing magnetic fields are separated by a layer of current called the heliospheric current sheet. Due to the tilt of the magnetic axis in relation to the axis of rotation of the Sun, the heliospheric current sheet flaps like a flag in the wind. The flapping current sheet separates regions of oppositely pointing magnetic field, called sectors. As the solar wind speed decreases past the termination shock, the sectors squeeze together, bringing regions of opposite magnetic field closer to each other. The Voyager spacecraft have now found that when the separation of sectors becomes very small, the sectored magnetic field breaks up into a sea of nested “magnetic bubbles” in a phenomenon called magnetic reconnection. The region of nested bubbles is carried by the solar wind to the north and south filling out the entire front region of the heliopause and the sector region in the heliosheath.
This discovery has prompted a complete revision of what the heliosheath region looks like. The smooth, streamlined look is gone, replaced with a bubbly, frothy outer layer.