Categories
Nature Science Universe

The Polar Day

The Midnight Sun shines 24/24h during the polar day
The Midnight Sun shines 24/24h during the polar day

Regions way above the Polar Circle, in the High Arctic, have already started to experience the polar day. Other Arctic regions are going to experience the phenomenon in the coming days. In Vadsø, the polar day already started on May 17 this year, and the Midnight Sun has been visible since, as well.

But what is the polar day?

Earth carries out two types of rotations: one around the Sun, during the course of a year, and the second around its own axis, during 24 hours. At the same time, Earth is inclined in respect with the Sun, at an angle of approximately 23°, and remains tilted at this angle during the whole year.

This means that the Earth is illuminated by the Sun differently during one year. At and around the summer solstice (sometime around 22nd June each year), Earth is inclined in such a way that the North Pole and the region around the North Pole, points towards the Sun, thus it is illuminated more and longer.

Just take a look at the first part of this video from the California Academy of Sciences, and see how Earth is illuminated by the Sun during a whole year.

You can see that the length of the polar day varies in function of latitude: closer you are to the North Pole, longer the polar day is. At the exact location of the North Pole, the polar day lasts no less than 6 months! At lower latitudes, but still above the Arctic Circle, the Sun never sets for a shorter period. The shortest polar day occurs on regions exactly on the Polar Circle (at 66°N), where the Sun never sets for only 1 day, which is exactly the day of the Summer Solstice!

The Midnight Sun

The Midnight Sun is a wonderphul phenomenon. It is what makes the sky bright at “night time” during the polar day, just like the Northern Lights brighten the sky during the dark period. It is a typical Arctic (and Antarctic) phenomenon, which occurs only during the polar day.

As the name suggests, here in the Arctic, the sun is visible in the sky at midnight, as well as the whole night and day, and it never sets below the horizon during this period. In Vadsø, the Midnight Sun will be visible this year until July 26.

And did you know that Aurora Labs has a special activity dedicated to discovering the midnight sun differently? Check it out here!

Regions below the polar circle experience a normal day/night cycle, which varies also in length, in function of the exact latitude.

And, by the way, the opposite of the polar day is the magnificent polar night! Have you ever experienced one or the other?

During the polar day, the Sun never sets below the horizon.
Categories
Stargazing Universe

Magnitude in Astronomy

The Full Moon has a -13 magnitude
The Full Moon has a -13 magnitude

You will often hear the term “magnitude” in Astronomy. Have you ever wondered what it meant? In this article, we’ll try explaining this term and we’ll see how to use correctly the “apparent magnitude” or “absolute magnitude” when talking about astronomic objects in the sky.

What is magnitude?

To keep things simple, in astronomy, “magnitude” refers to the brightness of an object in the sky. What we need to be particularly careful about, is the fact that the brighter the object, the smaller its magnitude! For example: a star with magnitude 1 is brighter than a star with magnitude 2! …And you guessed it, magnitude is unitless, that’s why we say “magnitude 2” or “2 magnitude”.

Apparent and absolute magnitude

Let’s imagine that we are on the top of a hill and we look at a very distant street light, down in the valley; let’s say this street light is 5 km away. From the top of the hill, we can see that the light is of a certain brightness. Now, imagine we start walking towards the street light. As we approach it, it seems that it gets brighter and brighter. So, how can we quantify the brightness of the street light if it seems to vary in function of where we are, relative to it?

In Astronomy, this issue is addressed by using two types of brightness – or, more correctly, two types of magnitude – for a celestial object: its apparent magnitude and its absolute magnitude. Most of us – at least in the near future! – will probably see the Moon, the stars, the planets and any other bright object in the night sky from our own planet, from Earth. All these objects will have a certain brightness, as they are seen from Earth, and this brightness is characterized by the apparent magnitude. So, the apparent magnitude of an astronomical object is the brightness of that object as seen from Earth.

As for the absolute magnitude, it is defined as the apparent magnitude of an astronomical object, as seen from a distance of approximately 310.000.000.000.000 km (the equivalent of 10 parsecs). The “usual” astronomer will just stick to the apparent magnitude; however, the absolute magnitude is important in research and studies, for example, for comparing the “real” luminosities of two or more objects.

Also, when talking about just “magnitude” – thus without specifying “apparent” or “absolute” – it’s the apparent magnitude which we refer to.

Magnitude values

Remember that a lower magnitude means a brighter object. But brighter of how much exactly?

The magnitude scale is logarithmic. Which means that the values which are to be displayed and compared on this scale are very far apart: the largest numbers are very much larger than the smallest numbers to be compared. To get a sense of it, magnitude 1 is 100 times brighter than a magnitude 6 (and not just 6 times brighter, as it would be the case on a “normal” scale).

Here are a few examples of magnitudes, to get an idea how this works:

  • The Sun has a magnitude of -27
  • The full Moon has a magnitude of -13
  • The International Space Station, when brightest, has a magnitude of -6
  • Planet Venus, when visible and when brightest, has a magnitude of -5
  • Sirius, the brightest star in the sky, has a magnitude of -1
  • Vega, the brightest star located in the Lyra constellation, has a magnitude of 0
  • The human eye, unaided, can normally see up to magnitudes of +3 – +6 (in function of the light pollution)

Can you now imagine how much brighter is the Sun (of magnitude -27), which you can’t even look directly at, compared to a Full moon (of magnitude -13)?

Magnitudes can be negative or positive, and the same rule applies: lower the magnitude – brighter the object.

And you guessed it: all “bright” objects have a magnitude, even the Sun, natural satellites or artificial objects (such as the ISS)!

The star Vega, besides being one of the brightest stars in the night sky and besides guiding us to find the Lyrids meteor shower each year in April, is also the reference point on the magnitude scale, having a value of 0.

Categories
Nature Science Stargazing Universe

The Lyrids Meteor Shower

Shooting Star
Shooting Star

Stargazers (almost) all around the world, get ready for an amazing stargazing event which starts tomorrow: the Lyrids meteor shower! Keep on reading to discover what a meteor shower is, and to find out how to see the Lyrids and other interesting facts about them! And don’t forget to prepare your wishes – maybe they will get granted, once you see the Lyrids!

What is a meteor shower?

A meteor shower on Earth usually occurs when our planet’s path intersects with the orbit of a comet. When a comet approaches the Sun, some of its ice vaporizes, leaving behind a stream of dust and debris, called a “dust trail” (which is different from a comet’s tail). When such debris – called meteoroids or micrometeoroids, in function of the size, and which is most of the time the size of a grain of sand -, enters Earth’s atmosphere at very high speeds (typically 70 km/s), it heats up because of the friction with the air in the atmosphere, which causes the particles to light up and glow. This streak of light crossing the night sky is called a meteor, or shooting star. So no, a shooting star is not a real “star” 😉

Meteors usually occur in Earth’s atmosphere at an altitude of above 50 km, and under 100 km. The glow can be fainter and shorter for smaller particles and it becomes brighter and longer as the size of the particle increases. The colour of a meteor can also vary, in function of the chemical composition of the particle!

And, by the way, a meteor that doesn’t burn up and which finally hits Earth’s surface, is called a meteorite!

The radiant

What is very interesting is the fact that the meteor particles in a meteor shower originate from a point called the radiant, and are all travelling in parallel paths.

But if we look at the sky, we see the meteors radiate in all directions. So how can this be? This is the effect of perspective! For example, if you sit in the middle of a straight railroad track and you look along it, you see that the two tracks converge at a single point, somewhere far away. This is exactly what happens with meteors in a meteor shower, but the effect is a lot more intense, due to the great distances where the meteor shower occurs!

The two parallel tracks seem to converge at a single point.

The Lyrids

The Lyrids are a meteor shower starting on April 16 and lasting until April 26 every year. This spring, its peak will be on April 22, so make sure you go out around this date, if you’d like to see this meteor shower in all its beauty; weather permitting, of course!

To locate the radiant of the Lyrids, you will need to find the Lyra constellation in the night sky. It’s not so difficult to find it, as Vega, the brightest star of this constellation, is one of the brightest stars in the night sky, with a magnitude of around 0, thus easy to see even in light polluted areas.

One way of easily finding Vega, is by drawing an imaginary line between two stars forming the well-known Big Dipper asterism, as shown in the below image:

Extend this imaginary line in the arrow’s direction, until you reach your first (very) bright star, which will be Vega. Be sure not to extend the line too long, as you will reach another quite bright star – Altair.

However, to see the actual meteor shower, you would need to find a place away from light pollution, as the shooting stars are not as bright as Vega! Their magnitude average somewhere towards the value +2, sometimes culminating with “Lyrids Fireballs”, which is the name given to some brighter meteors of this event. In addition, the Moon may make it more difficult to see this year’s Lyrids, so, if our natural satellite is troublesome, just wait for it to set, before trying to spot the meteor shower.

Naming and predicting meteor showers

Meteor showers are named in function of the constellation where they originate. So, the Lyrids seem to originate in the constellation of Lyra, hence their name!

The source of the dust creating the Lyrids comes from the C/1861 G1 Thatcher Comet – a long-period comet (415 years).

The Lyrids is a predictable event – that is, they occur because of the crossing of Earth’s path with the orbit of the aforementioned comet, which was last visible from Earth in 1861, when it was discovered by A. E. Thatcher (and is expected to be seen again in 2283!). The intersection of Earth with this comet’s orbit occurs each year in April, thus, the Lyrids meteor shower is then expected!

Did you know?

The Lyrids are the oldest reported meteor shower – since 687 BC!

Categories
Aurora Labs Northern Lights

Happy Easter! 🐰

Happy Easter from Aurora Labs in Varanger, Arctic Norway
Happy Easter from Aurora Labs in Varanger, Arctic Norway

Wishing you an amazing Easter from the amazing Land of the Northern Lights! Happy Easter! 🐰🍀🥚🐣😊

Une magnifique Pâques du magnifique Pays des Aurores Boréales ! Joyeuses Pâques ! 🐰🍀🥚🐣😊

#AuroraLabsNorway

Categories
Aurora Labs Vadsø

Aurora Labs’ New Safety Information Film

Aurora Labs Safety information film
Aurora Labs Safety information film

🇬🇧🇺🇸 Have a look at the new safety information film, in order to carry out a perfect activity in the Arctic with Aurora Labs, during your trip to Vadsø, in Northern Norway!

The French version is also available (scroll below)!

🇫🇷 Voici le nouveau film de consignes de sécurité, afin de réaliser vos activités sereinement en Arctique avec Aurora Labs, lors de votre voyage à Vadsø, au Nord de la Norvège !

La version en anglais est disponible egalement.

Acknowledgements and credits / Remerciments et credits:

Presenter/Présentatrice: Mégane Dubessay
Directed by/Réalisation: Sergiu Curelea
Video production/Production: Patrick Sérole, Sergiu Curelea
Post-processing/Montage vidéo: Sergiu Curelea
Text/Texte: Patrick Sérole
Music/Musique: Adam Vitovsky – “Stratosphere”
Copyright © 2021 Aurora Labs A/S