Auroras: What are they? When to watch them?

Some days ago, National Geographic published amazing photos of a ghostly green aurora borealis over Iceland (Image 1 and Image 2). Not only I wanted to share those images, but also to provide some information about auroras and how to plan a trip to watch them. A previous article about solar wind could be an introduction about such phenomena.

Image 1. Aurora Borealis in the late night skies above the frozen lake Kleifarvatn in Iceland on March 17, 2013.

Source: National Geographic

Modelling Mars Hydrology?

The interest about water and waterpaths in the red planet is quite old. In the late 19th century the Italian astronomer Giovanni Schiaparelli published a map of mars which looked like a river delta with several islands (Image 1). During the first decade of the 20th century the American astronomer Percival Lowell published books and maps with a detailed description of what he termed the "non-natural features". Lowell's channels were more like a network of artifitial adduction channels (Image 2). Such publications popularized the belief that these markings showed that Mars sustained intelligent life forms. Later studies showed that such channels were product of optical illusions due to technical limitations of the equipment of that time.

Image 1. Martian channels reported by Schiaparelli (left) and Lowell (right)
Source: Martian canal Wiki

Nevertheless, some years ago satellite missions revealed evidence of water in the form of river beds, geological forms that are typically formed from large amounts of water and frozen water (i.e., ice) in the martian poles.

Last March 7 2013, a team of scientists published a 3D reconstruction of buried flood channels in the Marte Vallis system, located in the Elysum Planitia. Using the Shallow Radar (SHARAD) sounder on the Mars Reconnaissance Orbiter, scientists were able to produce a tomographic visualization of the buried Marte Vallis channels. The SHARAD data revealed a complex channel system consisting of a broad ~40 km wide main channel that is adjacent to a raised bench, 120 km in width and incised by anastomosing channels formed around four streamlined islands. The main channel has an estimated depth between 69 - 113 m, which is comparable to the depth of the largest megaflood event on Earth. Such channels may have been generated by an ancient mega-flood event due to the release of groundwater.

Image 2. 3D visualization of the buried Marte Vallis channels beneath the Martian surface
Source: livescience

Scientists are now studying the source and scale of the channels, in order to comprehend Martian hydrologic activity and determine whether such floods could be related climate change on our planetary neighbour. Topographic data is already available, along with estimation of water volume. Now, I Wonder if it is reasonable to imagine that future studies will probably apply hydrologic and hydraulic modelling techniques in order to understand the past hydrological events that happened in the red planet. Will it possible to apply current modelling software, e.g. HMS, MODFLOW or RAS, to Mars? Which modifications would be required? Maybe the lower gravity would induce modifications to some parameters such as different manning or Froude number. Anyway, I think it opens a new door of opportunities for hydrological and planetary sciences

References & Additional Reading
3D Reconstruction of the Source and Scale of Buried Young Flood Channels on Mars
Ancient Mega-Flood on Mars Revealed in 3D
Could massive floods on Mars have caused climate change? New 3D maps suggest the red planet suffered major upheaval

World Water Day 2013: Water Cooperation

In 1993 the United Nations General Assembly declared 22 of March as the "World Water Day", as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. Since then, every 22 of March "World Water Day" was celebrated around the world, focusing on different topics each year.

2013 "World Water Day" will be celebrated under the theme Water Cooperation, within the framework of the International Year of Water Cooperation 2013, coordinated by UNESCO on behalf of UN Water. During the Water Cooperation 2013 Campaign, which includes the Year and the Day, efforts around the world at local, national and international levels will help to raise awareness on the potential and challenges for water cooperation, facilitate dialogue among actors, and promote innovative solutions for nurturing water cooperation.

Image 1. World Water Day 2013 logo

A high point of the Campaign will be the official World Water Day celebrations hosted by the Government of The Netherlands on 22 March 2013 in The Hague. Within the limit of capacity constraints, as wide a variety as possible of key stakeholders from inside and outside the ‘water box’ have been invited.

Water cooperation is a foundation for peace and sustainable development. Water cooperation contributes to poverty reduction and equity, creates economic benefits, helps preserve water resources and protect the environment, and builds peace.

The following video shares the Video Message from UN Secretary-General Ban Ki-moon on the importance of Water Cooperation, the theme of World Water Day 2013.

Additional reading:
UN World Water Day
UN World Water Day 2013
United Nations General Assembly Resolution 193 session 47

Not even Superman could have stopped Russian Meteorite

We still remember that last February 15, 2013, a meteorite hit the Russian Ural's near the city of Chelyabinsk. Several persons were injured, several building were damaged, and services such as internet, mobile, gas or electricity were interrupted  Such event revived speculations about a possible apocalyptic meteorite event. For instance, NASA announced that it has neither the funding to launch an infrared-sensing telescope in space to detect asteroids such as the one that blew up without warning over Russia last month, nor the capability to blast them out of the sky. When asked what would happen if we discovered one three weeks away from an impact with the earth, NASA's administrator Charlie Bolden answered: "The answer to you is, if it's coming in three weeks, pray." 

The other day I found a nice article about a fictional press conference given by Superman, in which he explains why he did nothing about the russian meteorite. I considered it very illustrative about the difficulties of preventing a meteorite hit.

Deviate it towards the Sun? 

First, is important to remember that Scientists could not detect the Russian meteorite because it came out of the daytime sky. Such kind of asteroids are nearly impossible to find ahead of time because telescopes can only spot asteroids during the night. Hence, when the asteroid was detected it would have been impossible even for Superman to deviate it towards the sun. The only 2 possibilities were either slow it down or destroy it. 

Slow it down? 

We must consider that the meteor was clocked at a speed of 40,000 miles per hour. When entering the atmosphere the meteor experiences a kind of crash, since it changes a vacuum environment (space) to  gas fluid environment (atmosphere). In order for an asteroid to slow down, the atmosphere absorbs the asteroid's energy and emits it as heat and light. Attempting to slow it down would have just burned it up anyway. Moreover, it would have absorbed more energy in the same time. Hence, it is reasonable to assume that it would have generated more heat and a brighter explosion. 

Destroy it? 

At the speed the meteorite was going, it contained around 440 kilotons, which is about 20 times the atomic bomb that hit Nagasaki. The atmosphere absorbed most of the meteor's energy, with only the aftermath of the fireball doing damage to Chelyabinsk. Destroying the meteor would have released all his energy at once. That would have been much worse.
For better understanding the possible damage of destroying the meteorite, let's take "The Bluegill Triple Primesh" test explosion of 1962. Such test exploded 410 kilotons at an altitude of 31 miles above the Earth. Nuclear researchers at ground zero could feel the heat on the ground and two of them even got retinal burns Now, considering that when the meteorite exploded it had an altitude of just 15 miles above the Earth (half the altitude of The Bluegill Triple Primesh test), we can imagine what would have happened when exploding a bomb of the same size at only half the altitude above Chelyabinsk. 

Animation 1. Meteorite hits Russia

Additional reading:
Superman Explains Why He Didn’t Destroy the Russian Meteor
Here's Why Astronomers Did Not Detect The Russia Meteor Ahead Of Time
Asteroid heading for New York? You better pray, NASA chief tells US Congress

Black Holes Factory?

In 2006 it was predicted that the world's most powerful particle accelerator, a.k.a. "Large Hadron Collider", would enable to create black holes. The Large Hadron Collider  is in an underground circular tunnel nearly 17 miles long at the world's largest physics laboratory, the "Conseil Europeen pour la Recherche Nucleaire" (CERN), near Geneva. At its maximum, each particle beam the collider fires will pack as much energy as a 400-ton train traveling at 120 mph. By smashing particles together and investigating the debris, scientists hope to help solve mysteries such as the origin of mass and why there is more matter than antimatter in the universe.

What is a black hole?

The basic idea of a black hole is simply an object whose gravity is so strong that light cannot escape from it. It is black because it does not reflect light, nor does its surface emit any light. For better understanding let's imagine the following example using Newton's law of physics.

The basic idea of a black hole is simply an object whose gravity is so strong that light cannot escape from it. It is black because it does not reflect light, nor does its surface emit any light. The basic ideas based on Newtons law had to be extenended when Albert Einstein completed his theory of general relativity, in order to include situations in which time and space could be greatly distorted.

The German mathematician Karl Schwarzschild investigated what would happen if all the matter in a body were concentrated at a mathematical point, and distinguished two black hole regions separated by a geometric feature called an “event horizon”. The world outside the event horizon is where we live and contains our universe, but inside the event horizon, space and time behave in very different ways entirely. Once inside, matter and light cannot get back out into the rest of the universe.

Figure 1. Artist's impression of a dust torus around a super-massive black hole. 

Source: http://www.spacetelescope.org/images/heic0409a/

Missconception: Is black hole a vacuum cleaner?

Most people think of a black hole as a voracious vacuum cleaner in space, sucking down everything around it. But that's not really true. Black holes can only suck matter under certain conditions.

• If a body orbits close to the event horizon in an elliptical orbit, it emits gravitational radiation, and its orbit will eventually decay in millions of years. 
• A disk of gas can form around a black hole, and through friction, matter will slowly slide into the black hole over time

How to create black holes?

The most common way for a black hole to form is probably in a supernova, an exploding star. When a star with about 25 times the mass of the Sun ends its life, it explodes. The outer part of the star screams outward at high speed, but the inner part of the star, its core, collapses down. If there is enough mass, the gravity of the collapsing core will compress it so much that it can become a black hole. When it’s all over, the black hole will have a few times the mass of the Sun. This is called a “stellar-mass black hole”, what many astronomers think of as a “regular” black hole.

Black holes also form when two orbiting neutron stars merge to produce a short gammaray burst, a tremendous blast of energy detectable across the entire observable Universe.

Using supercomputers researchers were able to simulate collisions among particles zipping near the speed of light. Such simulations have shown that black holes could form at lower energies than previously thought.

According to Einstein's theory of relativity mass and energy are related. The greater the energy of a particle, i.e., the faster a particle gets accelerated in a collider, the greater its mass becomes. Next, Einstein's theory explains that mass curves the fabric of space and time, generating the phenomenon known as gravity. As particles zip along within particle colliders, they warp space-time and can focus energy much as glass lenses focus light. When two particles accelerated are at each other, they distort to pancake shapes and then form a black hole, as shown in video 1. 

Video 1. Two particles accelerated at each other distort to pancake shapes and then form a black hole
Source: www.livescience.com/

The following video summarizes a first introduction about black holes.

Video 2. Black Holes:Warping Time & Space.
Source: www.space.com

Additional Reading:
Space Math: Black Holes
Black Holes
Despite Rumors, Black Hole Factory Will Not Destroy Earth
Mini Black Holes Easier To Make Than Thought

Garbage Patch in the Oceans

One of the problems of not considering the territorial distribution based on basins, is that we create the idea that we can solve problems by getting rid of them. For instance, we clean by throwing garbage (e.g. a plastic bottle or drinking straw) to the river without considering the effects downstream. Our location may be clean, but we just passed the problem (garbage) to the ones downstream. Something like sweep under the carpet.

I chose the example of plastic objects, since they are the main component of a big environmental problem in the oceans known as "garbage patches". Garbage patches are large oceanic areas where the currents concentrate marine debris. All the combined trash from sewer, solid waste, landfills and trash discarded in the street eventually ends up in the ocean. As material is captured in the currents, wind-driven surface currents gradually move floating debris toward the center the patches, trapping them in the region.

Figure 1. Example of marine debris

It is important to note that some missunderstood was created by using the term of "garbage continent". Actually, the patches are not visible as they consist of very small pieces with low density. Hence, they are suspended beneath the surface of the ocean.

Where are they located?

The major garbage patches are located in eastern and western Pacific patches. Recently, new garbage patches were reported in the North Atlantic and the Indian Ocean. Model simulation predicted the future existence of 5 potential patches as showed in the figure, and described in the table.

Figure 2. Location of potential garbage patches

Table 1. Characteristics of the potential garbage patches

Patch name	Eastern Garbage Patch	Western Garbage Patch	Northern Garbage Patch	Southern Garbage Patch	Indian Garbage Patch
Location	Pacific Ocean	Pacific Ocean	Atlantic Ocean	Atlantic Ocean	Indian Ocean
Surface [km^2]	8095000	715520	3625753	1296180	2183480

Is there a solution?

Unfortunately, there is no fast and easy solution. Cleaning? The time and cost of cleaning make that alternative an unfeasible one. Moreover, it is not a solution, since eventually the garbage will return to the sea and the problem will persist.

The solution consists on 4 concepts. Prevention, reduction, management and education.

Be conscious of plastics that you use and dispose of. Even the smallest pieces of plastic can pose a threat to the health of marine and animals and our planet. Try using reusable water bottles and shopping bags. Also try using products with less packaging and avoid single use plastics. The more we reduce plastics consumption, the cleaner we can keep our oceans.

Additional Reading:
Plastic Debris in the Ocean
The Garbage Patch in the Oceans: The problem and possible solutions
What we know about: The garbage patches
Huge garbage patch found in Atlntic too
New ocean garbage patch discovered
Help put a stop to ocean garbage patches
Garbage patch in lakes

Satellite detected Japan's 2011 earthquake and tsunami

Last March 11 the world remembered the earthquake and tsunami that hit Japan on 11 March 2011. New studies have revealed that this massive quake was also felt in space by ESA's satellite GOCE (Gravity field and steady-state Ocean Circulation Explorer).

GOCE was launched in 2009 with the main objective of mapping Earth's gravity, the fundamental force that pulls mass. In order to achieve its very challenging mission objectives, this slender, five-metre long satellite is designed to orbit at a very low altitude of just 260 km because the gravitational variations are stronger closer to Earth.

The following video provides more information about GOCE and gravity.

Earthquakes not only create seismic waves that travel through Earth’s interior, but large quakes also cause the surface of the planet to vibrate like a drum. This produces sound waves that travel upwards through the atmosphere.

Scientists from the Research Institute in Astrophysics and Planetology in France, the French space agency CNES, the Institute of Earth Physics of Paris and Delft University of Technology in the Netherlands, supported by ESA’s Earth Observation Support to Science Element, have discovered that GOCE detected sound waves from the massive earthquake that hit Japan on 11 March 2011. When GOCE passed through these waves, its accelerometers sensed the vertical displacements of the surrounding atmosphere in a way similar to seismometers on the surface of Earth. Wave-like variations in air density were also observed.

GOCE opens a door that will allow to understand our planet by looking up to the space.

The following animation shows how the massive earthquake that hit Japan in 2011 caused ripples in the atmosphere. As sound waves from the earthquake travelled upwards, they caused changes in air density that were detected by ESA’s GOCE gravity satellite as it crossed the wavefront.

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Additional reading:
GOCE: The first seismometer in orbir OCE/GOCE_the_first_seismometer_in_orbit
GOCE feels quake
GOCE