I'm about 7 weeks into a distance learning MSc in astrophysics with LJMU. Over the past two weeks the topic being covered was the interstellar medium (ISM) - the vast regions filled with gas and dust between the stars throughout the Milky Way.
During this time the weather has been mostly awful! But there have been a couple of clear nights and during those I've finally been able to try a modified DSLR on loan from a friend to get some images nebulae that are beyond the reach of my normal DSLR.
Here are two pictures taken by stacking dozens of images together. Both were captured through an 80mm refractor.
These nebulae are created when radiation from a hot, young star ionises neutral hydrogen nearby. When the electrons recombine with the hydrogen a very particular photon (corresponding to red light) is emitted. If the star was surrounded by a uniformly dense hydrogen cloud then the resulting nebula would be spherical, with the boundary of the nebula being the place where ionisations and recombinations balance. That's nearly the case for NGC280 above! But hydrogen clouds aren't necessarily distributed so perfectly around stars. In the picture of NGC1499 the nebula is created by the bright star near the bottom of the picture. The hydrogen cloud is clearly some distance from the star.
Hydrogen exists in several forms throughout the Milky Way. Clouds of hydrogen atoms are called HI (H-one!) regions. These ionised nebulae are called HII regions (not to be confused with H2 regions of molecular hydrogen).
I always enjoy getting pictures of these fantastic objects but the astrophysics course is adding a new layer of appreciation to what I'm doing.
Comet 2013 US10 Catalina will appear in the morning sky for UK observers from the end of November. It looks like it will become a binocular object at least; fingers crossed that it becomes brighter still!
Here's a finderchart showing the trajectory of the comet during December and early January.
Comet Catalina is tracking north very rapidly. During December it moves from Virgo into Bootes. On the first day of 2016 the comet will pass within 1 degree of Arcturus - the brightest star in the northern hemisphere of the sky. The contrasting colours of orange Arcturus and the dusty comet (perhaps with a green coma) should make an excellent photo!
Comet Catalina reaches perihelion (closest point to the Sun) on November 15th. The comet will be 0.82 AU (123 million km) from the Sun; between the orbits of Venus and Earth. Catalina won't be visible from the UK until it has moved further north, away from the Sun's glare towards the end of the month. Comet Catalina will be closest to Earth on January 17th 2016, at a distance of 0.72 AU (108 million km).
Comet Catalina was discovered by the Catalina Sky Survey in 2013. It is a dynamically new comet; it was perturbed from the Oort Cloud several million years ago and the trajectory after perihelion shows it will likely be ejected from the solar system - never to return.
Catalina is predicted to fade slightly after perihelion with brightness estimates putting it between 5th and 6th magnitudes. Dark skies away from light pollution should allow anyone with binoculars and telescopes to view the comet.
Wishing you clear skies!
The first session of my astronomy course went ahead at Berwick Educational Association this morning. I had some pretty bad technical issues right before the session, so I'm not able to post a Powerpoint right now.
However, much of what I discussed in the first part of the presentation - the history of geocentric and heliocentric theories, leading up to Kepler's laws and beyond - is covered in this earlier post.
The second part of my talk was a whistle-stop tour of the major planets and moons in the solar system. For an overview of the things I talked about in this part - visit the Nine Planets website (another casualty of Pluto's demotion from planethood!)
There wasn't time to show this video but I would have liked to given a bit more time (or less talking from me):
It's a scale model of the solar system constructed in the desert. You get a sense of not only how big and empty the solar system is but also how tiny the planets are in comparison to the distances between them!
Also in this session we had a brief discussion about the definition of a planet. All of these discussions in the astronomical community were brought about by astronomers figuring out the layout of the solar system in the past couple of centuries. Recent discoveries of Pluto-sized objects beyond Neptune finally brought the situation to a head in 2006. You can read some of the background to this in my presentation about Pluto here (warning: big PDF!)
The very last thing we looked at was the great gathering of the planets taking place in the morning sky this month. Here are how the planets are arranged this week.
Venus is the brightest - by some margin! Jupiter is the next brightest. It's quite close to Mars - not so bright and definitely orange in colour. The moon will be close to Mercury on Sunday morning. Mercury will be the most difficult planet to see because it's low near the horizon.
No sleep from Saturday night until Monday night. Was it worth it?
This was one of the darkest eclipses I've seen. For me, it rated as a 2 on Danjon Scale. Must've been a lot of clouds or dust in the Earth's atmosphere which prevented light reaching the moon.
I watched the eclipse through a 10 inch Dobsonian. The view was spectacular and the colours sublime.
The next total lunar eclipse for the UK will be in July 2018.
The simulation below shows the Earth and Moon at the time of the eclipse. It takes several hours for the moon to pass through the shadow.
The video doesn't show what really makes these eclipses special: at mid-eclipse the full moon is dimmed to an orange/copper colour by sunlight which has been filtered through the Earth’s atmosphere. The exact appearance and degree to which the Moon is dimmed is somewhat unpredictable because it depends on the state of our atmosphere at the time.
Visibility of the eclipse
In the UK: Where to look?
It's a full moon: if the sky is clear you won't have a problem finding it! The middle of the eclipse is at 3.46am (BST) and the moon will be in the southwest sky among the stars of Pisces.
The Earth’s shadow consists of two regions: a dark central region (the umbra) and a lighter boundary (the penumbra). The umbra is a region where all direct sunlight is cut off and the penumbra is a region where only part of the sunlight is blocked. You can witness the sight of these two shadows on a smaller scale by examining the shadow of your hand or another object as cast by desktop lamp.
The times at which the Moon enters and leaves the penumbra and umbra are as follows:
How to observe
You don't need big telescopes to observe a lunar eclipse; the changing face of the moon as the Earth's shadow falls across it will be obvious to the naked eye. Binoculars will provide a fine view of the moon too. In many recent total lunar eclipses a band of turquoise light, caused by light scattering through our ozone layer has been widely observed: binoculars and small telescopes should be enough to show this.
The ideal place on Earth to see this eclipse would be the north coast of Brazil - near the border with French Guiyana; the moon will be overhead at mid-eclipse. Good views for my wife's family in Venezuela too!
Future lunar eclipses
There won’t be another total lunar eclipse visible in its entirety from Northumberland until 2019, so local amateur astronomers will be trying to observe this one despite the unsociable hour of it!
This is quite a length blog post; it contains rough notes from a talk about planetary motion that I presented at The Trap Inn on September 10th 2015. Usually I'd be happy to post the presentation....but that would make it difficult to share the fantastic interactive flash stuff from the University of Nebraska-Lincoln that I used.
Read on to find out more!
Dr Adrian Jannetta
Guitar strummin' explorer of the universe. Mild mannered maths teacher by day and astronomer by night.