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Today’s APOD: Galactic Center

While I will not be posting every APOD I do wish to post the ones that I find appealing. This one also relates to the recent post of the all sky Milky Way.

This image concentrates on the Milky Way towards the galactic centre. Much of the galactic center is obscured by the dark lanes visible in this image. These lanes are present due to great clouds of gas and dust being located between us and the galactic centre. These clouds form dark nebulae. When gas and dust are located near a large star emission nebulae form. There are many emission nebulae present in this image.

The constellations visible in this image include Sagittarius, Libra, Scorpius, Scutum, and Ophiuchus. Emission nebulae visible include M8, M16 and M20. An example of a dark nebula in this image is the Pipe Nebula. There are numerous open clusters visible on the galactic plan and the globular M22 at a slight angle to the galactic plane.

For an anotated version of this image see the APOD website. Click the image below for a larger version.

Source: The Annotated Galactic Center

This video showcases 10 wonderful images taken by the Hubble Telescope.


Io’s Surface: Under Construction

Jupiter’s moon Io is the most geologically active body in the solar system. All the colouring visible in this image is the result of eruptions on this small moon. The colour is due to the presence of sulfur compounds.

It is thought that there could be as many as 300 active volcanoes on Io. It is estimated that these volcanoes eject enough material to cover the moons surface to a depth of 1 metre every century.

Prior to the flyby of Voyager 1 in 1979 it was thought that this moon would be a dead body with ancient cratering. We now know that Jupiter’s gravity has a great influence on Io. As the moon orbits it is slightly influenced by the planets other moons which does not allow the moon to become tidally looked with the planet. As a result the planet is subjected to tidal forces that cause heating in the moon’s interior. This drives the volcanism observed on Io.

Source: Astronomy Picture of the Day

All-Sky Milky Way Panorama

This is a stunning image of the Milky Way! The image takes in the sky if you could temporarily remove the Earth or was at a good distance away from our planet. The image is the result of taking 3000 images of the night sky and stitching them together. Many features of the night sky that are too dim for the human eye to detect are represented in the image. Particularly evident are the dark regions associated with gas and dust in the plane of the Milky Way. The Large and Small Magellanic Clouds are also distictive in the image.

If you are interested in the details of how this image was produced there is a paper available on the All-Sky Milky Way Panorama 2.0 website. The website also has a zoomable image version of the map.

Source: Astronomy Picture of the Day; Axel Mellinger

James Webb Space Telescope Deployment

After the Hubble Space Telescope has ended its operational life the James Webb Space Telescope will replace it. This telescope is scheduled to be launched in 2014. This instrument is designed to detect the light from the very first galaxies in the universe. This light is in the infrared region of the spectrum. Other objectives of this project include investigating the assembly of galaxies, stellar and planetary origins and the origins of life.

One question that is often asked is how we can see the light from the first galaxies as it occurred a long time ago. The reason is that they are located very far away from us. For example it takes 10 billion years for the light of a galaxy which is 10 billion light years away to get to us. Therefore, we see the galaxy as it was 10 billion years ago. It is likely that the galaxy has no resemblance to how we see it now. It is only time travel that is not science fiction!

The James Webb Space Telescope has a mirror assembly that is 6.5 metres wide, as opposed Hubble’s 2.4m. The larger mirror will collect more light making dimmer objects visible. The telescope will be placed into an orbit 1.5 million kilometers from Earth in the direction away from the Sun. In this location it will orbit the Sun at the same rate as the Earth. It will take 3 months for the craft to travel from Earth to this point. Also, if something goes wrong with it it will not be possible to repair it.

As the telescope will be observing infrared radiation it most be kept cold or it will emit infrared radiation making observations difficult, if not impossible. To achieve this the telescope will have a heat shield the size of a tennis court. The operating temperature of the instrument will be -225 Celsius or approximately 48 Celsius above absolute zero.

This is a video showing an animation of the James Webb Space Telescope being unfolded once it is in position. For more information you can go to the James Webb Space Telescope website.

The 3rd of August marked the 5th anniversary of the lunch of the rocket carrying the MESSENGER spacecraft. In the first 5 years the craft travelled 5.6 billion kilometres (3.5 billion miles). Its ultimate aim is to enter orbit around the planet Mercury. By the time it has entered orbit around the planet it would have passed Earth once, Venus twice and mercury three times. The aim of these flybys is to slow the craft to allow its insertion into an orbit around Mercury.

The main aim of the Messenger mission is to unlock the secrets of Mercury. The craft will examine the planet’s surface and magnetic field. By doing this we may discover the reason(s) for the planets high density, it geological history, the structure within the planet, the nature of its magnetic field and what the detected materials at the planet’s poles are.

The three flybys that have occurred already have provided some tantalising details.

The spacecraft is due to go into orbit around Mercury on the 18th of March of next year. For more information about the Messenger mission check the MESSENGER website. The video gives an over-view of the mission.


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