The Signs by a Rocket

For those who didn't know what was going on, on the rocket launch area at Esrange, you could see this trace in the clear blue sky in the city Kiruna. The trace is from a two-stage rocket from the Rocket-borne Experiments for University Students, REXUS campaign.

Photo by David Helgesson.

From a closer viewpoint I hade the opportunity to see the rocket in action!

An Artistic Masterpiece

It doesn't need to be the universe who creates something spectacular on the sky. Sometimes light (in this image street lamps) on Earth can create an artistic masterpiece in the sky. Looks almost like the northern lights, right?

Northern Lights (Aurora Borealis)

After a fantastic day in Narvik, this beautiful northern light appeared on our way home. Luckily I had my camera and could take my very first photo of this spectacular phenomena!

An aurora  is a colorful light that an be seen in the sky at the polar regions. Depending on which pole you see the aurora it is named northern- or southern light alt aurora borealis for the northern pole or aurora australis for the southern pole.

The aurora is caused by collisions from charged particles of high speed, with the Earths atmosphere. The light is created in the upper part of the Earths atmosphere, the ionosphere. 



Our Sun is the source of the high speed particles. When one of these particles enter the Earths atmosphere, it will collide with atoms and molecules in the Earths atmosphere. And when it does, the particle loses some of its energy to the atom. But the atom now has too much energy and therefore release a photon, a light. The particle continues to move, but now with lower speed, until it collide with another atom and loses some more energy. Also that atom will release a light. Every time the particle collide with an atom, the atom will release light and the particle will lose some more of its energy. Eventually the particle will have lost all its energy and will stand still. When the particle collide with different atoms and molecules we will see this light as an aurora.

Depending on the particles speed, the altitude of collision and what kind of atoms and molecules the particle will collide with, the light will look differently.  Depending on altitude, the collision with oxygen will give a green, red or brownish color. Collisions with nitrogen will give a color of blue or red. 



The most common color is green. Pure blue is the most rare one, as it is created at very low altitudes.


Halo, ἅλως

Too see phenomena on the sky you don’t have to go all day long waiting for the night to come. Even during sunlight you can be lucky to see something extraordinary! And today was my lucky day. The sun has been shining from a clear blue sky all day and when I looked out from my window at sundown I first thought I saw a rainbow. But how can there be a rainbow without rain? When rushing out for a photo I see a feeble arc around the Sun and I soon realise, it is a halo!

Halo is an optical phenomenon, also known as nimbus, icebow or Gloriole, that can be seen around the Sun or the moon. The name Halo is greek and means arc or circle and as the name describe, a halo is a colored or white arc. A halo is created by ice crystals in the upper part of the troposphere. Depending on the shape and orientation of the ice crystals, there will be different types of halos.

Photo: David Helgesson

With imagination you will see more

The ancient Greeks have named many of the well known constellations. Although, we today often use the name in Latin instead of the greek. The Greeks named the constellations after Gods, heroes and animals. Few of the constellations resemble their name. Often you need to have a lot of imagination to see the figures. One easy constellation to see without using too much fantasy is the Scorpius (scorpion).

Today the astronomers have been able to register 88 constellations, which you can find on any star map. I will here try to tell you little about them all and how to find them. Stay tuned for updates!

Brightness

While the southern part of Sweden have had snowstorm, the northern part have been blessed with freezing temperatures of minus 25 and a clear sky of stars and northern lights.

When you look up at the sky you can see that the brightness of the stars is different. Early as 150 b.c there was a Greek astronomer called Hipparchus who created a magnitude scale to gradate the brightness of the stars. Number one (1) symbolized the brightest stars on the sky while number six (6) symbolized those barely visible. Number two to four were stars in between. Refined, this system is still used today. But today, number one, on the newer scale, is 100 times brighter than a star with number six. Since the instruments are more accurate, the astronomers now days use two decimals to describe the magnitude of the stars. Also, for stars that are not visible for the naked eye, fainter than magnitude 6, the scale has been extended. Same goes for the other way, stars that are brighter are described with negative values.

One of the brightest visible stars on the sky is Canis Majoris, also known as Sirius. Sirius has a magnitude of -1.5 and can be found in the constellation Canis Major. 

“Watch up”

At this time of the year is often cold and dark, and many of us are dreaming and longing for the summer. But even this time of the year is bright in many other ways. Dress warmly and go out to a dark place and look up! A clear night you will see a different world, a world of magic and history. Constellation, planets and satellites are passing above our head every day. In colloquial meaning, a constellation is a group of celestial bodies, usually stars, which together appear to form a pattern in the sky. There are a lot of different constellations and I will try to tell you about them all, one by one. Also, I will describe and tell you about the planets and their historical meaning. At different time at the year we can see many of the planets with the naked eye!

Every clear night you could have the luck to see a satellite pass by. It looks like star unlike it moves across the sky. Try and see if you can find one tonight!

Polar Stratospheric Clouds, PSC

PSC are brightly shining clouds that can be seen before dawn or after dusk during polar winter. The clouds are created in the stratosphere, at altitudes 15000 - 20000 m, of chemical reactions of frozen water, nitric acid and sulfur acid which increase the ozone destruction.