Category Archives: Observing

Anticrepuscular Rays over Southern Tuscany


This glorious image from C) Ollie Taylor (limks below), via ESA illustrates wonderfully one of my favorite things – Atmospheric Optics.

Keep an eye on the sky and you too can see many of the optical effects described in my favorite atmospheric optics site, oddly enough named Atmospheric Optics – check it out and see what you can put to use, I think it’s great fun when it works out. The coolest thing I think I’ve seen and I may have a picture of it is the supernumerary rainbow.

Here is ESA’s caption to this great photo: This panorama comprises five images showing the Sun setting over the medieval and Renaissance town of Montepulciano, southern Tuscany.

While the enormous ball of hot gas that is our star cannot be directly seen, its presence is suggested by the radiant streams of light emanating from below the horizon — called anticrepuscular rays, or antisolar rays.

Despite appearing to meet at a point just below the horizon, the rays are in fact near-parallel beams of sunlight. Similar to the way that parallel railway lines seem to converge at a point in the distance, this is a trick of perspective; while these rays of sunlight do eventually meet at the Sun, it is a great deal further away than they make it appear.

Earth’s atmosphere, made up of gases, particulates and clouds, has shaped the way humans have seen the Sun for as long as they have been able to perceive it, for example making the white-hot star appear yellow against a blue sky, masking the infinite blackness of space.

However, as soon as we get past this protective layer, the true effect of our raging Sun becomes apparent in the fast changing, and potentially harmful environment of space, where space weather rules.

Space weather refers to the environmental conditions in space as influenced by solar activity; besides emitting a continuous stream of electrically charged atomic particles, the Sun periodically emits billions of tonnes of material threaded with magnetic fields in colossal-scale ‘coronal mass ejections’.

These ‘solar sneezes’ can and have caused significant disruption to Earth’s protective magnetic bubble and upper atmosphere, affecting satellites in orbit, navigation systems, terrestrial power grids, and data and communication networks. A recent ESA study estimated the potential impact in Europe from a single, extreme space weather event could be about €15 billion.

For this reason, ESA is planning a new mission to monitor the Sun’s activity and provide early warnings. The spacecraft will be positioned between the Sun and Earth at a special position called the fifth Lagrange point. From here, it can observe the ‘side’ of our star, detecting rapidly changing solar activity before it reaches Earth, providing much-needed warning of extreme weather events, allowing measures to be taken to protect and minimise any possible damage to satellites in orbit or infrastructure on Earth.

More images by UK-based photographer Ollie Taylor can be found on his website, or via Instagram and Facebook.

The Perseids are Here!

My best recollection of the Pereids came from one night years ago now. I was in the back seat of my car, looking upwards through the hatchback window. No, not like that! I was the backseat passenger of a car load of students learning how to initiate intravenous therapy, actually the first class where the class was starting IV’s on each other. Anyway the 45-minute journey was an incredible Perseid viewing experience – as was the EMT class.

Ok, I digress. GO OUTSIDE AND LOOK TO THE NORTH! Not just now but tomorrow too!

Orbits

Orbital mechanics is a very interesting topic.

Usually when you see an orbital track displayed on your computer you see a nice sine-wave pattern.

Take the International Space Station for example or perhaps the newly launched Sentinel-3B.

Then we have geostationary satellites like GOES-17, oh yes it is orbiting.

Have a look at the seemingly odd orbit of the recently launched TESS.

Thanks to N2YO for those great links and check that site out – great stuff!

Scott Manely has a good video out: T”he Most Confusing Things About Spacecraft Orbits”

May Skies

Hubble’s Tonight’s Sky May 2018

If you have good skies you should be able to catch the peak of the Eta Aquarids. The best time to catch these bits of debris from Halley’s Comet is 06 May in the hours before daylight.

The Morning Sky

If you get a chance to look at the sky before daylight you will be treated to (R to L): the Moon, Jupiter, Saturn, and Mars all lined up across the sky. Provided the moonlight does not over whelm Saturn and Mars they all will be visible at the same time.

Jupiter in particular will be very bright so so worries there. You should also be able to see a few of the giant planet’s moons.

The above graphic is from Stellarium showing the line-up before sun rise (click to see a larger version).

Hopefully you won’t be clouded in, I think I am going to be.

Also apparently there is some ridiculous claims this line up is going to cause an increase in volcanism and earthquakes. In a word: NO. That’s just plain crazy.

What’s Up for April

Ahhh, April the temperatures are moderating and it is becoming more comfortable to be outside. Usually a lot of moisture in the air but still good viewing.

I can’t even get into the N2YO site at times – busy. Tiangong is very close to coming in, predictions are 01 April (tomorrow) at 16:45, I will update this later as the estimates become more clear.

Oh and the internet problems are still going on; although there is a work order in, I don’t expect resolution until Monday. I did have an epiphany of sorts and am connecting through my phone and it seems to be working.

Tiangong-1 Coming Down

The Chinese space station Tiangong-1 is losing altitude at an ever increasing rate as the station and the Earth feel that mutual attraction. Of course Earth is going to win.

Right now the station is at about 221 km and losing about 0.20 km per orbit.  Yesterday that loss per orbit was about 0.13 km.

Currently the estimate is 03 April plus or minus a week.  Looking at ESA’s estimate above  the orbit is going to continue the increase in downward motion until  Tiangong-1 feels the increasing density of our atmosphere and begins to slow down appreciably.  When that happens we reach a tipping point of sorts and the spacecraft or what is left of it (yes there will be pieces) will pitch steeply and eventually hit the Earth.

Where will that tipping point be?  That’s the big question.   We are about to find out the answer.

You can follow orbital decay on N2YO.com.  I think we are just days away.