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.

The Orion Nebula

Click to be able to see Venus

Last night was a clear winter night. That means a lot of stars were visible. Also the Moon, Venus and Jupiter were close together in the sky. I was even able to see Venus with my naked eyes during the day because the Moon was so close. It might be hard to see in this photo but Venus is close to the bottom right corner. It was so amazing to actually see one of the planets in the bright blue sky while the sun was still up.

Orion nebula without enhancements

Anyhow, that wasn't what this blog post was going to be about. The Orion nebula. A nebula you can also see with naked eyes (it's the middle "star" in the sword). Although I'm guessing not in daylight. I have seen it through binoculars and telescopes though. I've tried to photograph it through a telescope as well, but since I haven't got a camera adapter it was hard to hold the camera still. To take these photos I used my Canon EOS 550D (Rebel T2i) and my Canon EF 70-200mm f/4L USM lens.

Orion nebula like I see it through my telescope

I took ten 1-second exposures to reduce the star trails. Then I used an old version of a program called DeepSkyStacker to stack the photos together. I made two different versions of the photo. One almost black and white that looks close to what you see when you look at it with a telescope. And one with some more colour in it.

Orion nebula with colours

Using a 200mm lens on a crop-sensor camera still makes the photo way too big. So I had to crop away most of the photo since there wasn't anything in it that I would use. As you can see in the photos I didn't make the crop in exactly the same place for all three photos and that was mostly because I'm lazy. At least they are the same size.

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.