Twice are not custom, here is a summary of the news space in recent days. And this time she is still busy and exciting. So first, an overview.
We reach the maximum of the cycle of solar activity, but it shows a bit more sluggish than expected. NASA has crashed a rocket which launched a satellite Taurus to 400 million. And the galaxy NGC 247 is closer to us than expected ...
The Sun in the resting phase
I mentioned a few days ago a large solar flare which took place recently. Well it is not very representative of the current activity of the Sun. Our star has a cyclic operation: every 11 years, she arrives at a phase of maximum activity, reflected by the large number of sunspots and thus the intrinsic activity of the Sun (flare, coronal mass ejections etc.). Looks like the sun to its full cycle, with a closeup of a sunspot.
A sunspot is actually an area a little colder at the surface of the star. This is due to the magnetic field intensity in this region, which inhibits the movement convection (movement of molten material from center to periphery), and therefore reduces the surface temperature.
We are approaching the solar maximum (which should happen for 2013), yet the activity of the star is well below expectations. The Sun has the air of being in a phase of minimum activity. The lowest round since a century, according checheurs.
known the existence of sunspots since Galileo observed them in the seventeenth century, and we follow the evolution of life since the eighteenth. We're currently number 24 in the cycle, the maximum should be reached around 2013. But since the peak of Cycle 23 in 2001, the activity is lower.
But then, what is it due? To answer this question, researchers rely on simulations. They have thus updated the importance of a stream of plasma (matter at very high temperature) Southern. Just below the "surface" of the star, a plasma stream perpendicular to the equator connects the two poles and then plunges into the heart of the Sun. The simulations show that the rate of this flow is a factor affecting solar activity. A rapid current in the first part of the cycle and slow in the second would cause a general weakness magnetic which would result in a phase of activity minimum. Scientists make a link between this type of solar inactivity and the "little ice age" of the seventeenth century.
The important thing about this discovery is not the scientific dimension that the possible consequences. It has become capable, thanks to solar observation satellites such as STEREO, predict the "weather" solar short term. It is now (about to be) able to predict the operation of the Sun on a longer term of at least 11 years. One example would seek to provide for manned space missions during solar minimum, or so to prevent the passage of aircraft at the poles during periods especially active.
Crash
The weather satellite that has unfortunately crashed into the ocean Friday was the ironic name of Glory. Yet it was of great importance in climate research. Glory should have an interest in how aerosols affect the climate. However aerosols are a concern to the uncertainties Intergovernmental Panel on Climate Change (IPCC).
For NASA, and the builder of the rocket and Satellite Orbital Sciences, is a dismal failure. $ 424 million went up in smoke. And Orbital Sciences, is also the second failure in two years. That recall that space launches are not always reliable. So a bit of chauvinism: the Ariane rocket, after the Russian Soyuz is the most reliable pitcher on the market.
Okay, but what happened Friday on the Taurus rocket-XL? Well it's simple, the launcher fairing did not become detached.
The cap is the part located at the top of the rocket that protects the satellite during launch, and gives the rocket more aerodynamic. It is therefore useful when one is still in the atmosphere. Once in the vacuum of space, no need for aerodynamics or protect the payload. And as a cap, it's heavy, it will always rid
soon as possible to reduce the launcher. (Left: Ariane 5 drops her cap once out of the atmosphere) The Taurus rocket failed to get rid of her cap, she found herself overweight. The engines are not expected to orbit such a mass, it crashed into the Atlantic ...
1, 2, 3, Sun!
Here NGC 247, a spiral galaxy relatively close to us: 11 million light years. It is part of the Sculptor group, a group of galaxies close to our Local Group. She just made a good one million light-years ahead: researchers have long overestimated the distance. Here's why.
Cepheids are a special type of variable stars very regular. Their brightness varies with a period which is proportional to their absolute magnitude (brightness intrinsic to the star as if it were viewed from a few million miles away, not to be confused with the apparent magnitude, that is to say, as seen from Earth). The method used for estimating their distance is simple: we calculate the period of variation of the star, we deduce its absolute magnitude. By a simple comparison of its magnitude and the apparent brightness of the star, we deduce its distance.
The Cepheids are detected within a few nearby galaxies, and thus we calculated their distance. But in the case of NGC 247, researchers realized that the light emitted by the Cepheids the Galaxy went through dusty disk (which surrounds the entire galaxy spiral worthy of the name). Part of this light is absorbed. The apparent magnitude of stars is therefore underestimated. It is thought to see them later, when we actually see them through a veil of dust.
much for today. But before you leave, a goodie: a video of the last good definition takeoff of the Space Shuttle Discovery , taken from the camera located on one of the SRB (Solid Rocket Booster, the two long white tubes, which are makes the solid rocket boosters that give the shuttle more than 90% of the power takeoff).
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