Jupiter and Venus

Last night Jupiter and Venus were pretty close together. I had originally planned to go out and take a photo when they were closer to the horizon, but since the thick dark clouds came in fast I had to put on my 14mm Samyang lens and take a quick photo before they disappeared completely.

Edit: Today we had a clear sky so I went out and got this photo using my 30mm Sigma lens.

Stars twinkle, planets don't

Sirius, Jupiter and Betelgeuse

It's easy to think that all the small dots in the night sky are stars. They aren't of course. There are at least 5 planets that you can easily see with the naked eye. Mercury can be seen with the naked eye, but being so close to the Sun it's usually at dawn or dusk and not at night you can see it. The others are Venus, Earth (duh...), Mars, Jupiter and Saturn. So how can you tell the difference between a star and a planet if you just happen to look up at the night sky? Stars twinkle. Yes the nursery rhyme is true. Twinkle, twinkle little star. Although they aren't exactly small they appear small to us.
The photo above illustrates the difference between stars and planets. Left to right it's Sirius, Jupiter and Betelgeuse. Why I chose to have two stars is because they are different colours so they appear to twinkle differently. Jupiter as you can see does not twinkle at all. So why is that? From what I can guess, and what seems logical to me, is that stars shine light in all wavelengths and Earth's atmosphere lets the different wavelengths through at different speeds so that it appears to twinkle. That would also explain why they twinkle more near the horizon. Planets on the other hand reflects just a few wavelengths of light from our Sun so they always appear to be a solid dot.
Even if I got this right I'm sure there are people out there that can explain it better.
The photos are 10-second exposures taken handheld with my Canon EOS 550D (Rebel T2i), Canon EF 70-200mm f/4L. At least the stars make really nice artworks that way.

Can we build a planet from asteroids?

My original plan for today was to write a blog post about something different, but I haven't gotten my sleep the last few days and my mind started wandering. That's never a good thing...
Anyhow, I had this thought about the asteroid belt between Mars and Jupiter: Would it be possible to use the asteroids to build a planet?
I would like to mention that I have no real education in these matters so these are just my thoughts. Also as I said I haven't been sleeping enough lately so my mind works in mysterious ways at the moment.
If we had rockets strong enough to slow down the orbits of the asteroids to make them collide with each other at low speed differences*, could that make them stick together and form a larger planet? If it's possible to make them collide at low speed differences the individual gravity of each asteroid would join together to make a single point of gravity over time I guess. If that time is 100 years or 100 000 years, or even more, is not the point. If we can pile on asteroids on Ceres to make it larger than the Moon, that would be awesome.
We might also have to take into account that to actually hit one asteroid with another asteroid it's probably similar to shooting the head of a thumbtack from a mile away...
Then there's Jupiter. The massive gravity from Jupiter might rip the asteroids away from each other before they have a chance to join forces. Even after it could too I guess.
Maybe someone with real knowledge about these things will tell me it's impossible, but hey if we don't dream we don't progress. Maybe someday in the future we have the kind of energy that's needed to boost rockets like that.

*If two cars collide head on the damage is greater than if one car rear-ends the other car when both cars are traveling at about the same speed.

Astrophotography

One of my biggest interest has always been astronomy. The emptiness of space is fascinating to me. Especially the night sky on a clear night is amazing to look at. The next step then is of course to try and take photos of it.
There are a few ways to do that. You can use a wide angle lens and get whole constellations in the photo. You can use a telephoto lens (for example all photos in this blog post is taken with my Canon EF 70-200mm f/4L lens and then I've cropped out a lot of the black surrounding the object I wanted) and get a single object. Or you can use a telescope to get even more magnification.

The moon is always a good place to start when trying to take photos of objects in the night sky. Not only does it change appearance every day, it's easy to see the "oceans" and craters with the naked eye. It's also the brightest object in the night sky.

Further away Venus is really bright. Our closest planet neighbour. It's the second brightest object in the night sky. Sometimes, like in this photo, you can see it in the west after sunset and sometimes you can see it in the east before sunrise. It's breathtaking to imagine that if Venus had had an atmosphere like the one we have here on Earth then there could've been life on Venus. It's almost the same size as Earth too so if there was no life we could've colonized it.

Then we have Jupiter. The massive gas giant. The third brightest object in the night sky. Seen here in a photo with its four largest moons. With my telescope I can actually see some of the bands and the red spot. However I have no equipment to attach my camera to the telescope so I can't take those kinds of photos... yet.

Occasionally the Moon passes close to one of the planets. On one such occasion I was able to take this photo. You can see the Moon in the upper right corner and the small dot in the lower left corner is Jupiter.

Of course it's not just in the night sky that you can see objects in the sky. I took this photo of the sun just minutes before sunset one day when it was a thick fog and cloudy.






I don't have that much chances to take good photos of constellations. Even though I have a wide angle lens I live in a small city. That means the sky is always polluted with light from the street lights and cars and stuff like that. I have a list of constellations that I do want to take photos of. Oh and I would love to take a photo of the Milky Way someday. When I do I'm sure you will see the photos here on this blog.