Nowadays, scientists have the ability to observe the universe across many wavelengths, including those that cannot be seen by unaided human eyes – such as infrared and gamma rays. However, there is still some “blind spots” for the astronomers in the electromagnetic spectrum, such as the high energy X-rays region.
In order to clarify our view of these cosmic X-rays, NASA has just launched the Nuclear Spectroscopic Telescope Array (NuSTAR), a sci-fi looking space observatory that will allow us to better understand the physics and chemistry behind the most extreme objects in the universe.
NuSTAR is going to observe the same kind of X-rays used in medicine – when the doctors need to take a look at our bones – and in airports – to see what’s inside our luggage. Although we have spacecraft able to take X-ray images, like NASA’s Chandra and ESA’s XMM-Newton, these facilities aren’t able to get sharp images of this energetic form of light.
Surveying the Extreme Universe
The NuSTAR’s primary mission – projected to last for at least two years – is intended to provide a detailed survey of both stellar and supermassive black holes. Although being known as objects capable of swallowing pretty much everything nearby – even light – the region around the black holes – called the accretion disk - emits vast amounts of X-ray radiation, produced by the friction between the pieces of debris orbiting the black hole. NuSTAR is equipped to detect these radiation bursts and locate black holes that would be otherwise invisible.
It’s also going to analyse the young-supernovae remnants, more specifically, the radioactive nuclei produced by the exploding stars. These nuclei are the key to understanding the conditions in which each explosions occurred, the nuclear ignition, structure and dynamics of the explosion, giving us clues as to how exactly the elements are formed in the hidden core of a star.
The brightest objects visible to NuSTAR are the jets emitted by supermassive black holes – that can be found in the core of most galaxies – in a specific kind of galaxy known as a blazar. These are a form of active galaxy that produce jets composed of particles travelling in very high speeds that happen to be pointing towards the Earth – therefore we see them much brighter than we would otherwise. By observing the variation of the light intensity of these beams, we’ll be able to figure out how the black hole’s accretion disk looks like, as well as the physical structure and composition of the jets.
And that’s not all: the probe will also peer at the Solar corona, the outer atmosphere of the Sun. This region is known for its extreme temperatures – as a matter of fact, even hotter than the Sun’s surface. By studying the corona, we can get a close-up look at the particle acceleration processes similar to those that take place in objects like supernova remnants and black hole jets.
Looking Further than Ever
What makes NuSTAR able to archive all these goals is its ingenious focusing mechanism: a pair of Wolter-I mirrors pointing at the same patch of sky. Moreover, in order to improve its reflection capacity, these mirrors are coated with structures known as “depth-graded layers”, made of a mix of low and high density materials.
The unprecedented sensibility of NuSTAR – along with the data from the other observatories – will allow us to study the universe as never before, from the surface of the Sun to the galaxies at the other edge of the universe, going through the most extreme objects known by humankind.
NuSTAR has successfully reached orbit and is preparing for the commencement of its observations.
Over tonight and the early hours of tomorrow morning a true once in a lifetime event will occur. Venus will be seen to make a solar transit. “What is such an event you may be thinking” and why “is this one so special?”
The transit event is very similar to the much more common solar and lunar eclipses so we can start their.
A solar eclipse occurs when the Sun, moon and Earth line up exactly so allowing the moon to block a portion (or indeed the entirety) of the sun’s disk as seen from a region of the Earth’s surface. A total solar eclipse (one where the Sun is totally obscured) occurs roughly every 18 months. This comparatively short interval is helped by the proximity of the moon to the Earth and the large size of both the moon and the sun (the potential region of overlap between the two disks is hence quite large).
Lunar eclipses occur when the position of the moon and earth are reversed and the Earth blocks out the sun as seen from the surface of the moon such events occur much more frequently with at least two occurring each year and they also last for a longer duration aided by the larger size of the Earth compared to the moon.
Transit events occur because of the same principle as a solar eclipse, though in the case of transits the moon is replaced by the other planet. Transit events are much much rarer than standard eclipses (either lunar or solar).
The distance between the Earth and the planet involved is much, much larger compared to the distance between the Earth and moon. This means that as viewed from Earth the planet involved in the transit (either Mercury or Venus in the case of Earth) is much smaller than the apparent size of the Moon. Combined with the Sun remaining the same size in comparison there is a smaller possible region of overlap which in turn means that the chance of the overlap between the discs of the sun and and planet occurring is much smaller.
The occurrence of the transits relies on the exact line up of the orbits of the planets involved and the correct orbital inclination – so the planet that tracks in front of the sun actually passes across the disc of the sun rather than above or below it. As such line ups occur very rarely such transit events are are exceptionally rare. With transits of Venus visible from Earth occurring in pairs once every 121.5 or 105.5 years separated by 8 years in the pair.
What will the transit look like?
As the transit occurs the shadow of Venus will appear to track across the surface of the sun as a dark shadow over the course of several hours.
The transit has already begun and you can see the live NASA stream here:
Myself and a group of my friends will be attempting to observe the event ourselves in the early hours of the morning so stay tuned!
Well thanks to the good old British weather we saw absolutely nothing!
I hope your luck was better!
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The flow of content on the site has unfortunately been somewhat meagre for the last little while with A-Level and equivalent exams ongoing.
Thankfully these draw to a close within the next few weeks and normal posting will then resume.
In the meantime we will be covering the upcoming Solar Transit of Venus on the 5th and 6th of June with (if all goes to plan) myself bloging updates through the night and hopefully with a few photographs of my own in the morning.
- The Worlds with Two Suns | The Young Astronomers on Binary Stars Blitzed – Updated
- Ed.A on Image of the Week – A Peculiar Pencil – 18/09/2012
- Saint on SS 433 – A Magnificent Microquasar
- SS 433 – A Magnificent Microquasar » The Young Astronomers on Binary Stars Blitzed – Updated
- John Fairweather on A Star’s Death Giving Life to a Monster – Recovered
- New Post from @Lightbulb500 - The Worlds With Two Suns - bit.ly/RUQKuk 7 months ago
- We will also be posting about our plans for the next while both here, on the blog and our Facebook page - on.fb.me/RUQCuA 7 months ago
- Sorry for the long delay in posts, we have all been very busy. We will hopefully have a more regular post program shortly. 7 months ago
- Our latest Image of the Week highlights the star cluster NGC 1929 and the surrounding nebula N44 - bit.ly/QbkwY6 - by @Lightbulb500 8 months ago
- New post by @Lightbulb500 - How to Understand Spectra – Part 2 - bit.ly/NveYoX 9 months ago
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