“Muslim scientists and clerics have called for the adoption of Mecca time to replace GMT, arguing that the Saudi city is the true centre of the Earth.”
Using three X-ray space telescopes – ESA’s XMM-Newton, JAXA’s Suzaku and NASA’s Chandra – Japanese astronomers have discovered that the black hole at the centre of our galaxy was much more active 300 years ago, when it gorged on a large feast of nearby stars (for full details, see ESA’s press release).
Imagine looking for a black object on a black background, and you will appreciate the difficulty in observing black holes! However, when a star or gas falls in towards a black hole, it gets extremely hot – millions of degrees centigrade hot! Anything at this temperature will give off X-ray radiation. So the best way to find a black hole is to look for X-rays in space – the tell-tell sign of something falling towards a black hole.
Not only that, but those X-rays can reflect off clouds of gas… which is exactly what has been observed. A cloud of gas near the centre of our galaxy suddenly brightened. What astronomers believed happened is that the black hole at the centre of the galaxy had a big feast which released large amounts of X-rays. Those X-rays then travelled for 300 years until they collided with the neighbouring gas cloud and caused it to glow. And now, we are just seeing that gas cloud glow.
This means that, if we had X-ray space telescopes 300 years ago, we would have been able to witness the black hole at the centre of the Milky-way enjoying its feast!
We have seen the super-massive black-hole at the centre of the Milky-way feed before, but the feast 300 years ago was a million times bigger than anything we have seen in recent times.
If you want to know more about black hole, why not watch our planetarium show Black-holes: the other side of infinity?
Not all these missions will become reality.
Which ones would you choose?
The above banners have been taken from the ESA website.
Spring is here, so it is time to say goodbye to Orion until next winter! By the end of April, it will by hidden by the glare of the Sun, and during June the Sun will be directly above Orion.
The Sun is setting later and later, setting now at 8pm summer time. In fact, the Sun is setting 40 minutes later at the end of the month than at the start. Although the nights are getting shorter, making it more difficult for observing, it is also getting warmer – a welcome relief to anyone who has been observing in sub-zero temperatures this winter!
The Moon is a wonderful sight in the evening for the first few weeks of April, but the full Moon is on the 20th, making it very difficult to see any but the brightest stars. Last quarter is on the 28th of April, so that is another good opportunaty to observe the fainter objects this month.
The only planets visible in the evening this month are Mars (look west for a red object all evening, although it gets very low in the sky after midnight), and Saturn (high in the south at sunset, and setting in the west at 3am).
Saturn is easy to spot this month since it is so close to the bright star Regulus, in the constellation of Leo (Saturn is the slightly fainter of the two). On the night of the 14th of April, the Moon is just to the right of the pair, and on the following night, the Moon is just below the pair.
If you have never seen the rings of Saturn before, then those two nights are the best time to be amazed by the sight, with the Moon acting as a very helpful guide, and Saturn being at its highest point in the sky at sunset in the evening – very convenient!
We know summer is rapidly approaching, because the summer triangle is once again visible in the evening sky, rising during April at around 10pm.
And for those staying up really late, Jupiter is very bright indeed. Just look towards the south-east to see Jupiter rising at 3am. If you have binoculars, take a closer look and you may be able to see up to 4 moons orbiting around Jupiter.