CSA - AuroraMAX Project - Live broadcast of the Northern Lights from Yellowknife
And from this page:
HT Dan.
And from this page:
The AuroraMAX Observatory
The live camera turns on automatically once the Sun sets below the horizon in Yellowknife. As we approach the winter solstice in the month of December, the camera will turn on several minutes earlier each day (since darkness falls earlier). For example, during the week of September 27, 2010, the live feed will begin around 8:50 p.m. Mountain Time (10:50 Eastern). The auroras tend to be most easily visible about an hour or so after dark. If this is past your bedtime, you can watch the daily aurora replay in the Gallery section, choose a date, or watch the AuroraMAX team’s favourite movies in the Featured Videos section.
The AuroraMAX observatory’s main camera is an all-sky imager, which gives a 180-degree field of view to capture the entire night sky so that you don’t miss any auroras (in Yellowknife, auroras typically light up the sky from one horizon to the other, and very often seem to be right over the observer’s head as well!). Here’s a tip to get used to the image: imagine lying on your back, and being able to see all around you (even behind you).
If you don’t see auroras right away, be patient. Auroras tend to come in waves, called auroral substorms. You may have logged on in between two substorms, or before it is dark enough to see the Northern Lights. Other factors can also reduce visibility locally, including clouds, rain or snow on the observatory’s Plexiglas dome (you may want to check the weather locally to see if weather might be impeding your view of the auroras). the Moon. The full Moon can make the auroras appear paler and less colourful. The Moon also can also reflect off the observatory’s dome, and tends to reflect off snow (especially on the ground).
This montage shows the AuroraMAX observatory's main camera in the foreground, along with one of its images of an aurora (round). While most skywatchers are used to viewing a small section of the Northern Lights as seen in the background image, the 180-degree AuroraMAX camera actually captures the entire aurora as it stretches across the night sky from West to East.
You might be missing a Flash plug-in to run the videos. You can either download the plug-in free of charge from the following website http://get.adobe.com/flashplayer/, or watch the videos in html (on the main page www.asc-csa.gc.ca/auroramax, scroll down to the bottom of the page and select "Html version.")
The AuroraMAX replay is a time-lapse video of the previous night’s auroras condensed into one or two minutes.
Why are images from the AuroraMAX Observatory round?
AuroraMAX’s main camera shoots a 180-degree view of the sky, which produces a circular image. The circumference of the circle is actually the horizon all around the camera (if you look carefully, you will see the tree tops even in the upper portion of the image).
When can I see auroras?
Aurora usually begin to appear in the hours following dark locally when skies are clear, and tend to intensify around midnight. Visit Astronomy North for the aurora forecast for tonight and the coming days. Local weather and sky conditions in Yellowknife (including sunrise and sunset) are available from the Government of Canada’s Weather Office.
Why are auroras common in the North?
Northern skywatchers see the aurora more frequently because of the position of the auroral oval, a crown of geomagnetic activity around the north and south magnetic poles. Communities located beneath the oval regularly see bright auroras.
Why is Yellowknife ideal for viewing auroras?
Yellowknife’s latitude (62 degrees North) and semi-arid subarctic climate (which averages less than 300 mm of precipitation annually) make for ideal viewing conditions for the Northern Lights. The auroral oval is often found directly overhead, resulting in auroral displays almost every night (even when the solar wind is calm).
When are the Northern Lights visible in southern Canada?
During periods of increased solar activity, intense solar winds will cause the auroral oval to stretch like a rubber band and expand southwards. When this occurs, southern latitudes are treated to bright auroras.
Where is the AuroraMAX Observatory located?
On your home computer! The AuroraMAX Observatory is a virtual facility that provides aurora enthusiasts everywhere with instant access to Yellowknife’s Northern Lights via the Internet.
The Northern Lights
What are the Northern Lights?
The Northern Lights (also known by their Latin name, the aurora borealis) is a natural display of light commonly seen in the northern sky (auroras in the southern hemisphere are known as the aurora australis). Auroras occur when charged particles from the Sun collide with gas molecules in Earth’s atmosphere, producing energy in the form of light.
What is the solar wind?
The solar wind is a continuous flow of charged particles from the Sun.
What is the relationship between the solar wind and auroras?
As the solar wind flows past Earth, its charged particles travel along magnetic field lines that descend into Earth’s atmosphere near the north and south magnetic poles. These particles (electrons and protons) collide with oxygen, nitrogen and other molecules of gas in the atmosphere, resulting in auroras.
What is a substorm?
A substorm is a brief but intense surge in geomagnetic activity that produces very bright, fast-moving auroras.
Why are auroras so colourful?
The colours of the aurora are determined by the composition of gases in the Earth’s atmosphere, the altitude where the aurora occurs, the density of the atmosphere, and the level of energy involved.
Green, the most common colour seen from the ground, is produced when charged particles collide with oxygen at lower altitudes (around 100-300 km). Occasionally, the lower edge of an aurora will have a pink or crimson fringe, which is produced by nitrogen molecules (around 100 km).
Higher in the atmosphere (300-400 km), collisions with atomic oxygen produce reds instead of greens. Since the atmosphere is less dense at higher altitudes, it takes more energy and more time to produce red light (up to 2 minutes), whereas green light can be made quickly at lower altitudes (about one second).
Hydrogen and helium can also produce blue and purple, but these colours tend to be difficult for our eyes to see against the night sky.
The Sun
What is Solar Maximum?
Solar Maximum is a period of increased sunspot activity that is the peak of an 11-year solar cycle. The next Solar Maximum is expected to occur in 2013.
What are sunspots?
Sunspots are regions on the surface of the Sun that are about 2000 degrees cooler than surrounding areas, and therefore show up as being dark patches. Sunspots can be several times larger than the Earth itself, often occur in groups and can last for a couple of weeks.
Sunspots occur when the Sun’s magnetic field becomes twisted. Unlike Earth, the Sun rotates faster at the equator than at its poles (the equator rotates every 27 days, whereas the poles only make a complete rotation every 30 days). This creates “knots” in the Sun’s magnetic field that produce sunspots.
Sunspots form bubble-shaped loops on the surface of the Sun that can erupt, spewing out huge amounts of electrically charged (ionized) gas into the solar system (this is known as a solar prominence). When this stream of charged particles happens to be pointed in the direction of Earth’s magnetic field, it produces intense auroral displays.
What is the sunspot cycle?
The sunspot cycle refers to an 11-year cycle of sunspot activity that varies from Solar Minimum (a period with very few sunspots) to Solar Maximum (a period with numerous sunspots, solar flares and coronal mass ejections).
How do we know which sunspots will cause bright auroras on Earth?
In order for a sunspot to generate auroras on Earth, the solar wind it releases must be pointed in the general direction of Earth. A newly formed sunspot near the middle of the solar disc provides an early warning that a fast-moving burst of charged particles is heading in our direction. As they reach Earth’s magnetic field and penetrate into the atmosphere, intense auroras begin to surge across the sky.
HT Dan.
No comments:
Post a Comment