Sometimes you can have diffuse auroral curtains and arcs that have small gaps. These gaps are usually thinner than the arc thickness next to the gap, and they look like a black auroral curtain embedded in the bright auroral glow around them. The black auroras can have curls and other structure. The sense of direction of these curls is opposite to that of regular auroral curtains.

Aurora is a luminous glow of the upper atmosphere which is caused by energetic particles that enter the atmosphere from above. This definition differentiates aurora from other forms of airglow, and from sky brightness that is due to reflected or scattered sunlight. Airglow features that have "internal" energy sources are more common than aurora, for example lightening and all associated optical emissions like sprites should not be considered aurora.

Weak aurora, with a small, barely visible auroral oval in this image from the POLAR VIS instrument. The bright crescant shape light on the left is from the sun illuminating the Earth. When the solar wind is calm, the aurora might only be at high latitudes and might be faint, but there is still aurora. In order to see aurora, however, the sky must be dark and clear. Sunlight and clouds are the biggest obstacle to auroral observations.

The Aurora Borealis or Northern Lights are mesmerizing, dynamic displays of light that appear in the nighttime Arctic skies. They appear in many forms -- pillars, streaks, wisps, haloes, and curtains of vibrating color. Auroras are caused by collisions between electrically charged particles from the sun and gases in Earth's upper atmosphere.

The aurora extends over a very large altitude range. The altitude where the emission comes from depends on the energy of the energetic electrons that make the aurora. The more energy the bigger the punch, and the deeper the electron gets into the atmosphere. Very intense aurora from high energy electrons can be as low as 80 km (50 miles). The top of the visible aurora peters out at about 2-300 km (120-200 miles), but sometimes high altitude aurora can be seen as high as 600 km (350 miles).

The immediate cause of aurora are precipitating energetic particles. These particles are electrons and protons that are energized in the near geospace environment. This energization process draws its energy from the interaction of the Earth's magnetosphere with the solar wind. The magnetosphere is a volume of space that surrounds the Earth. We have this magnetosphere because of Earth's internal magnetic field. This field extends to space until it is balanced by the solar wind.

This is a difficult question to answer. It is easy to say that the aurora makes no audible sound. The upper atmosphere is too thin to carry sound waves, and the aurora is so far away that it would take a sound wave 5 minutes to travel from an overhead aurora to the ground. But many people claim that they hear something at the same time when there is aurora in the sky.

Most visible aurora comes from precipitating electrons. However, the magnetosphere also shoots energetic protons toward the atmosphere. Both electrons and protons are charged particles, and they are not free to move in just any direction (see question 6). The curtain shapes of aurora results from this restriction on the motion of charged particles. When an electron spirals along the magnetic field into the atmosphere, it stays on or near this field line even when it makes a collision.

The ultimate energy source for the aurora is the solar wind. When the solar wind is calm, we tend to have very little aurora, when the solar wind is very strong and perturbed, we have a chance of intense aurora. The sun turns on its own axis once every 27 days, so an active region that produced perturbations might again cause aurora 27 days later. The solar wind takes a few (2-3) days to get here on its way from the sun.

Treatment is very safe for the skin. There are many advances in the Aurora technology that make it one of the safest hair removal systems available for all skin colors. There are no long-term health hazards from light or electric energies used in the Aurora. Both have been used for decades in medicine, surgery, and aesthetics.

The composition and density of the atmosphere and the altitude of the aurora determine the possible light emissions. When an excited atom or molecule returns to the ground state, it sends out a photon with a specific energy. This energy depends on the type of atom and on the level of excitement, and we perceive the energy of a photon as color. The upper atmosphere consists of air just like the air we breathe.

This is very difficult to answer, and a question we might get once every few minutes when there is an active storm. The factors if it is visible where you are are many. Location, latitude, light pollution by moon or cities, clouds, etc. etc. Read the latest forecast notes on http://www.spacew.com/. And understand that the question when exactly it will start is asking when the rain will start when rain is expected in the weather forecast.

Please take a look here. For some starting points on exposure times, check this page. Also the information in the gallery for each photo on http://www.northern-lights.no/ and http://www.spacew.com/ is a good source of information. On this site we added a page with tutorials on how to edit photos of the aurora. For tips on actually shooting the aurora in the field you better check out one of the links mentioned before.

Aurora Student is the student information system. You can log in and register, check your program, transit to Arts or Science from University 1 or declare your Major and Minor. You can also access fees, grades, transcripts, booklists and tax forms. Please check out the Registrar's Office website for more information or go directly to Aurora Student.

We are happy for our customers to contact us by phone or email and we will let you know where our nearest stockist is or you can come into our Aurora Candle shop at the Subiaco Pavilion Markets.

because being colorblind, I don't see in color, and instead of driving me and everyone around me nuts by constantly asking if one color is the same as what I used last time, I just do DT as line art, occasionally i add some color, or do a special color pic, but otherwise i just say screw color.

NBP's Econo Black - NBP's own formulations - This molybdate black goes directly on zinc die cast. After the molybdate coating is applied, the parts are submerged in a seal composed of chromates and phosphates that enhance the salt spray resistance of the coating. An organic coating, water dip lacquer, is applied as a final coat to protect the finish and improve appearance.

Black henna, a green powder that smells like frozen peas, is neither black nor henna. It is indigo, Indigofera tinctoria.

We have two macadamia nut trees in Vista, CA. They are 15 years old. Until last year they have been healthy and prolific, but last year and this before the nuts/husks fall to the ground, a black fuzz forms in the crack and then the husk becomes black and moldy. Do you have any suggestions about what is happening and what we can do to stop it? Thank you for your review of my question. Black mold is usually associated with either aphids or white fly. Check your trees for an abundance of ants.

The organism Gloeocapsa produces a dark-pigmented sheath to protect itself from ultra-violet rays. By the time the black streaks are noticeable, the algae usually have been growing for months or years - the result of generations of dead algae cells built up over time.

The orb is what The Wise One sealed the ‘ancient power’ inside before his demise, to protect everyone else from what had happened to his people.

Anyone who wants a solution to shaving, waxing, plucking, or electrolysis. There are a few medical conditions that contraindicate people from treatment, which will be discussed with your Aurora clinician during consultation. The Aurora and/or the Polaris uses gentle light and electric energies to restore skin to a more youthful state.

Treatment is very safe for the skin. There are many advances in the Aurora and Polaris technology that make it unparalleled for skin safety, without compromising effectiveness for treatment. There are no long-term health hazards from light or electric energies used in the Aurora or Polaris. Both technologies have been used for decades in medicine, surgery, and aesthetics without adversity

The magnetic field confines the motion of auroral electrons. Think of it as painted magnetic field lines. The electrons that make the aurora are charged particles, and they are not free to move in just any direction. Magnetic fields impede motion of charged particles when they try to cross the magnetic field. Charged particles can move freely only parallel to the magnetic field (either in the direction of the field or against it).

Since the aurora takes place at about 90-100 km altitude, only the atmosphere at or above that height is affected by aurora. Some ionization may occur a few tens of kilometers further down, and can have effects on radio wave propagation. Ham radio operators may find that at some frequencies, radio waves will not propagate far. The major effect of the aurora is, however, at the altitude range of 100-200 km.

Most people are quite familiar with the Northern Lights, also known as the aurora borealis - the auroras of the Northern Hemisphere. The equivalent term for the Southern Hemisphere auroras, is the Southern Lights, or aurora australis.

Thanks to the folks at Course Technologies and their "Great Internet Hunt" web page, this is a frequently-asked question. The information below may or may not be what they are asking you to find. Our advice is free and you get what you pay for.