Wednesday, February 25, 2015

How to view a solar eclipse safely

Solar eclipse is a wonder - partial and definitely a total. Many people wants to observe this marvelous celestial event and some will go great distance to a place of totality. Here are some tips and rule which will enable you to view the event safely. Remember that direct viewing of the sun with the eyes is dangerous and doing it with an optical aid such as binoculars or a telescope may cause permanent damage and blindness. Do not use improvisations such as old floppy disks, old films etc.
This warning is true even if the eclipse is 98%. Never look at the sun directly. If you are so fur tune to have a full solar eclipse you can look at the sun halo during the short period of totatily.
The instructions are also suitable for a Solar eclipse observations. 

After this warning here are some options to view a solar Eclipse.
Solar Eclipse Glasses
  1. Get special solar eclipse glasses. These are special glasses, with special filters which block almost 99.99% of the sun light. Such glasses are not expensive, and will be very useful for future solar eclipses (there will be a full solar eclipse in 2017 in the USA). However, such glasses are to be used with the eyes only, and not through a telescope or binoculars!
  2. If you have a telescope you might want to consider to purchase a Solar Telescope Filter for it. There are generic filters which are suitable for many telescopes and there are vendor specifics filters for the vendor brands. You can buy at Amazon or at your local dealer. These filters are attached to the telescope, in front of it and block the light BEFORE it enters the telescope. Such filters MUST NOT be used instead of an eyepiece. The light from the sun must be blocked before it is concentrated by the telescope (the filter is not strong enough to block the light after the telescope concentrates it). During the observations make sure that the filter is strongly attached and that no one removes it by mistake (especially when you are doing an observation with a group of people).
  3. If you are really into solar viewing, you should consider purchasing a dedicated solar telescope. Such telescopes as the Coronado PST are dedicated and safe for solar viewing and are useful to observe other interesting solar phenomena such as the sun prominence.
  4. If you have a telescope and you want to project the image to a large audience you can use the projection method. Basically you project the image of the Sun to a dark surface (make it in the shade) and focus. Sunspots are very visible this way. This method is appropriate for small refractors and Newtonian telescopes, but not for SCT telescopes. If you are not sure how to do it or if it is suitable for your telescope do not do it! Personally, I do not like this method very much since I think that if you already have a telescope, it is a very little investment to buy the filter. Take note that the intensity of the sun light may harm the telescope as it creates heat which can harm the plastic and the optics so do it at your own risk. Also make sure that no-one ever tries to look through the telescope at the sun. Full instructions are here
  5. You actually don't have to own a telescope to project the sun. You can build a great homemade pinhole projector from simple boxes. You will get a small image of the sun and you will be able to see a dark spot on it. Watch the below video to see how (It is recommended to watch in on full screen)
  6. If you do not have the solar glasses nor a telescope, join your local astronomy club. Any eclipse is a major event and professional observatory and local amateur groups will provide the means for the public to view the eclipse properly and safely.
  7. Join a live web cast of the event. Many observatories from around the globe will host live cover of the eclipse. You will be able to view it safely from your home. However, I think that this is the less preferred option to view an eclipse (just one step away from not viewing it at all) as there is no replacement for viewing with your own eye.

Projecting the sun through a telescope - a bit risky but possible

Venus and Mars conjunction

You definitely can't miss bright Venus in the western sky just after sunset it is so amazingly bright that it is often misplaced for a coming airplane. It is easy to miss Mars which is a bit below Venus and much dimmer. We have just had another nice conjunction of Venus and Mars.
Why conjunctions are so fascinating? Maybe because it is our way to see that planets really moves, since all other stars are fixed, and just the planets wanders between them. Also such conjunctions are important in astrology but we know all for the better that this is rubbish. the truth is that such conjunction are a pleasure to observe and watch for several days seeing the daily relative movement of the planets.

I've started to track the pair about a month ago when Venus and Mercury were in conjunction and Mars was way above, Last week it rained a lot and I hardly got a chance to photograph the pair. Here is a photo from 19/2/15. Mars is a bit above Venus (You might need to enlarge the photo to see it properly)
 Venus and Mars between the clouds
Venus and Mars between the clouds -19/2/2015
I could not take any photos on Friday 20/2 since I am an orthodox Jew. However it was cloudy and rainy and even as I tried to observe the pair (and the new moon) all that happened was that after a lightning storm I was wet.

Saturday night 21/2/15 the storm was over, the skies were clear and I took the following photos. Venus is extremely bright, Mars is a bit red and their position do look different from the picture above. Also noticeable the nice earth shine on the moon which appears as a while

Venus and Mars 21/2/15
Venus and Mars 21/2/15
The part of the moon which is not directly lit by the sun still gets some light bounced back from Earth. This light returns to our eyes so we are able to see some details on the entire moon although it is just 3 days old!
A day passed and Venus is already above Mars. Mars is very dim, since there were lots of cirrus clouds in the sky, but you will be able to see it below and to the right of Venus. he moon is much further above
Venus and Mars 22/2/15
Venus and Mars 22/2/15

Venus and the moon 22/2/15
Venus and the moon 22/2/15
The conjunction is over. Mars is in its way down to disappear behind the sun. Venus is climbing up to be in a really close conjunction with far far away Neptune (Try to watch is with telescope on the fourth of Mars. Finding Neptune will never be as easy as aiming to Venus) and in July with Jupiter. Planets keep travel in our skies and give us great observations.

For further reading

Thursday, January 29, 2015

New moon setting timelapse

One of my hobbies is to spot the new moon as early as possible. Seeing the moon and setting the months in accordance to the new moon setting has an important role in the old Hebrew calendar. The current Hebrew calendar is based on calculations so the beginning of a new month can drift a day or two from the actual day that the new moon is seen from Israel.
This month, the new moon was at 21/1/2015. I was able to see the moon about 15 minutes after sunset. It depends on the moon age (26 hours in this case) and its location and of course the observer location. The moon was about 5 degrees north of the ecliptic which means that it could be seen in the sky more than a hour after sunset. this was an easy moon to spot but seeing it while there is still light is still a challenge. Venus however is so bright that it was easy to see it even before sunset. This is no wonder since you can see Venus during the day easily.
So here are just a few pictures before we are going to talk about timelapses.

The first moon is from 17:17 and it may take a while to find the thin crescent of the moon.

The new moon
The new moon (you will see it when you enlarge the photo - just click over it)
After some minutes it is darker and Venus is clearly visible and also Mercury almost at the same line of the moon and to its left.
The new moon Venus and Mercury
The new moon Venus and Mercury

The new moon Venus and Mercury
The new moon Venus and Mercury
If you enlarge the next photo you will see some red light from a passing airplane over the moon.
The new moon Venus and Mercury
The new moon Venus and Mercury

I am getting addicted to timelapses. They are fun to plan, easy to carry out and looks so charming. You don't need fancy equipment. You can do them with your smartphone as well. I am using a Canon700d for the timelapses. I used an intervalometer which enables me to see the number of photos I want and the time between each photo. If you use a smartphone there are bunch of software which will do that for you, but you will probably needs an external power source. also a tripod adapter is necessary for best results (You can buy them for few bucks in china, the intervalometer as well). I will write a longer article about timelapses in the future.

This time I thought that a photo every 2 seconds will be OK. I changed the photo resolution to a moderate size (there is no need for 24M files for an HD video), and let it work for 80 minutes. I had 2400 photos and used the freeware "virtual dub" to create the following timelapse. make sure to watch it on a full screen and in HD resolution (you might need to open it in YouTube site  for it)

The video starts from the first time I saw the moon until Venus sets. As it gets darker more stars become visible.
So what's next? Next month 19-22 February, Venus and Mars will be very close in the sky. In the 20th, the new moon will also be there for US observers (I will miss that :-( ), so check up your gear, see if you need a larger memory card, get your intervalometer or suitable APP, do some tests and try to take your own great timelapse.

Sunday, January 11, 2015

Venus and Mercury Conjunction

Venus and Mercury are in conjunction and it is easy to see the pair at southwest just after sunset. Bright Venus is visible immediately but it will take some 20 minutes to see Mercury. Their closet distance was during 9-11/01/2015 at about half a degree (just like the full moon), but they will be close together during the following few days.

Lets start with the better video from 2015-01-12 and thew whole story just after
As always better to watch on you-tube site with 1080hd resolution!

The first photos are from 11-Jan-2015. My point of view was quite good, as the pictures include the Israeli International airport (TLV), so you can see airplanes takeoff (In a curved S shape) and land.

As I tried to photograph, a bunch of very young curios kids got around me asking so many questions and bumping the tripod from time to time which of course damaged the video since it changed the composition and I have to throw away blurry photos. However they were so cute and asked so many questions - What is a star? How big it is? What is its name (4 times, I hope they got it finally). What is this star (Orion constellation at the east)? Where is the polar star? and so on... You simply can't be crossed at such nice kids!
Here are some photos and the video. The camera is Canon 700d with 18-250 Sigma lens.

Venus Mercury and an airplane landing
Venus Mercury and an airplane landing (bottom right

Venus, Mercury and an airplane taking off
Venus, Mercury and an airplane taking off
The video is a composition of about 200 photos taken during 50 minutes period Until Venus dropped behind the clouds (make sure to watch on HD 720 at least)! Don't miss the airplanes! They add a lot to the video.

I wanted to try again so I went today (12-Jan-2015) to a different place with a friend and tried a different approach, which basically is to photograph much more frames. I came out with around 1400 frames. Toward the end of the timelapse you will be able to see Mars as well at the top left - 3 planets and even four if you count Earth,
Few photos:
Venus and Mercury - 2015-01-12
Venus and Mercury - 2015-01-12

Venus and Mercury - 2015-01-12
Venus and Mercury - 2015-01-12

Venus and Mercury - 2015-01-12
Venus and Mercury - 2015-01-12

Venus and Mercury - 2015-01-12
Venus and Mercury - 2015-01-12
And the video from January 12th 2015

Related articles:
Venus and Jupiter conjunction
Venus and the Pleiades