The Half-Astrophysicist Blog

The Triple Planet Conjunction of May 2013

I have been posting some pics on facebook, twitter and google+ the last week of the current triple planet conjunction in the evening sky. Last night the three planets made their closes approach to each other. Mercury, Venus and Jupiter were all easily visible to the naked eye and this is a great time to be watching them. You can clearly see the movement from night to night as their relative positions change.  Here are some pics from Tucson last night.

First a close up of the trio.


Next some wide shots of the three. There were low clouds on the western horizon so I got to watch the three play hide and seek amongst the clouds.IMG_6829 IMG_6837 IMG_6843 IMG_6848

Although the night of closest approach is past, they will still be visible together after sunset and worth looking at for several more days as they continue to move away from each other. Jupiter will be lower each night while Mercury speeds higher and above Venus each night. Eventually Mercury will turn around and pass Venus as Mercury dives back toward the Sun and Venus continues to get higher in the sky (by this time, Jupiter will probably be too low to see easily).

Enjoy this one…we only get these triple conjunctions every few years.


May 27, 2013 Posted by | Astrophotography, Conjunctions, Jupiter, Mars, Mercury, Observing, Solar System | | Leave a comment

The Moon Occults Jupiter on Christmas

Many people, including myself, saw the Moon and Jupiter very close together on Christmas. They appeared a few degrees apart depending on where you were on the Earth and when you looked.

However, for observers in South America, the Moon actually passed in front of Jupiter and covered it up for about an hour. You don’t need a telescope to watch this, but if you have a telescope, a camera and some skill, you can capture this on video. And someone in Brazil did just that and posted a killer video to Youtube.

This video is sped up by a factor of five so you don’t have to watch it quite so long. The detail on Jupiter is amazing. Look closely as Jupiter disappears behind the Moon and you can see a dark dot on Jupiter which is the shadow of one of its Moons transiting the surface of Jupiter. Look at Jupiter when it comes out from behind the Moon…you can still see the shadow on the planet but it has moved!

There are several close encounters between Jupiter and the Moon in early 2013 and there will be more occultations for some lucky people living in certain parts of the world. I already looked and I am not one of those lucky people, but I look forward to more wonderful videos and pictures of these events!

December 28, 2012 Posted by | Astrophotography, Conjunctions, Moon, Occultations, Solar System | | 1 Comment

Look West, Young Man, Look West

Tonight after suset, there will be a lovely grouping in the early evening sky. No telescope will be required to see it. A little over a week ago, I posted pics I took from a trip to San Diego showing Mars, Spica and Saturn. This trio is still visible in the western sky after sunset. Tonight they will be joined by the crescent Moon. Here is a chart showing what it will look like from Tucson at about 8:00pm tonight.

In this image, the four objects make a rhombus.  The Moon moves fairly quickly, about its diameter every hour, so you may see a slightly different configuration depending on if you look earlier or later than the time I set here. To make a map for your location, try Stellarium, a free planetarium program available for both Mac and Windows (it’s what I used to make this chart).

You can also look at these bodies and think about the missions we currently have in operation around three of them: Saturn (Cassini), the Moon (Lunar Reconnaissance Orbiter and GRAIL) and Mars (Curiosity, Opportunity, Mars Reconnaissance Orbiter, Odyssey and Mars Express). Spica is about 260 light years away so it will be a while before we have a mission around it!

I will be trying to photograph this gathering of course, but the summer rains and clouds have been plentiful in Tucson recently so they odds are not in my favor. Of course I am always happy to see photos taken by others as well!



August 21, 2012 Posted by | Conjunctions, Observing, Solar System | Leave a comment

Sunset and Planets From San Diego

I am in San Diego this weekend and finally got a chance to do a little photography. Sunset was up first from the harbor of course. While taking some pre-sunset shots, I got this nice one  of the setting Sun with a bird flying across the field of view.


I kept shooting as usual. Much to my surprise, I got got a hint of a green flash at one point. I saw this visually as well as on the camera just as the left part of the Sun disappeared behind a tree lined hill.

I waited for it to get dark and walked out on a pier to get a pic of a couple of planets and Spica. A few people were sitting on the end of the pier making for a nice foreground. Spica is the lowest of the three bright ones, Mars is above it and Saturn is the top.

Finally, a nice wide shot of the whole harbor with the same three objects. You can see bright lights from the Navy base across the bay.

Nice night in San Diego.


August 13, 2012 Posted by | Astrophotography, Pretty Pictures, Solar System, Sunset | , , | Leave a comment

The Moon Rejoins Jupiter and Venus

In late February, the Moon, Jupiter and Venus had a nice gathering in the western sky after sunset. At that point Jupiter was above Venus. A month later, the three are together again. This time, however, Jupiter and Venus have swapped places with Venus being higher in the sky.

So, here are tonight’s pics. First, Kitt Peak in the distance shortly after sunset.Image

Next, a wide shot of the planets. Venus is at the top, Jupiter below it and the crescent Moon at the bottom.

ImageNext, a closeup of that crescent Moon with Earthshine.

ImageOne more shot of the planets, slightly narrower field of view.

ImageThe next couple of nights will be great times to watch the sky. Sunday night, the Moon will be near Jupiter, Monday night the Moon will be near Venus and Tuesday above them (later in the week the Moon moves progressively farther from the planets each night).

March 25, 2012 Posted by | Astrophotography, Conjunctions, Solar System | Leave a comment

Quick Planet Pics

Yep, lots still going on. Keep looking this week. First, Mercury is still visible but getting more difficult to see. Got it tonight. Had to use binoculars at first but found it naked eye eventually. Got a nice shot of it above a palm tree.

Of course the main event is Venus and Jupiter. I went out a little later tonight and they are drifting farther north so I positioned myself a little differently in my townhome courtyard tonight to get the pic.

Yep, that’s an orange tree! The oranges are not ripe yet, still pretty small but I thought they made an interesting foreground for the pic! Keep looking the next few nights. Tonight is technically the closest approach, but March 15th is the date of the actual conjunction (a fancy astronomy term meaning they have the same right ascension. Right ascension is kind of like longitude but in the sky).

March 13, 2012 Posted by | Astrophotography, Conjunctions, Observing, Solar System | 1 Comment

Daytime Venus

Today is a great time to see Venus during the day. The Moon is passing just a hair less than three degrees north of the Moon (around 22UT which is about 3pm MST or about now). Find the slender crescent Moon and Venus is about three finger widths (held at arms length) beneath it. Very easy to see today.

And pretty easy to photograph. Took this shot a few minutes before 3pm in Tucson.

February 25, 2012 Posted by | Astrophotography, Moon, Observing, Pretty Pictures, Solar System | | Leave a comment

Planet Party in the West After Sunset

There is a lovely gathering of planets in the west after sunset. Most people are focusing on the obvious targets of Jupiter, Venus and the Moon this weekend. However, keen eyed observers will notice Mercury has joined the party as well. I got a couple of shots tonight. From top to bottom, we have Jupiter, Venus, the Moon and Mercury. To the right of Mercury is a bright plane. There is a major air corridor out there so planes are not uncommon in that part of the sky.

In the second shot, I got a bright plane right above Mercury. This was intentional to give people a guide to help find Mercury in this pic.

Although it looks like they are close together, in reality, they are far apart. The Moon is a mere 240,000 miles away. In reality, Mercury is about 108 million miles away right now, Venus is about 87 million miles away and Jupiter is a whopping 502 million miles away. Space is big!

You can see great views the next two nights. Saturday night the Moon will pass by Venus and on Sunday night it will be close to Jupiter. Mercury will get higher in the sky each night and easier to see until about March 4th when it will turn around and head back toward the Sun. Venus is getting higher in the sky and Jupiter is getting lower in the sky each night. They will pass very close to each other on March 10th. It’s a great time to keep watching the western sky after sunset!

February 25, 2012 Posted by | Astrophotography, Moon, Observing, Pretty Pictures, Solar System | | 2 Comments

A Close Encounter Between Venus and the Moon

Venus and the Moon are engaging in their dance the next few months in the evening sky. Tonight the crescent Moon was well below Venus.

Tomorrow night the Moon will be below Venus and Thursday night it will be just above Venus giving two more excellent opportunities to see this nice pairing in the night sky.

But that’s not all. Venus is nice and far away from the Sun right now which and the Moon provides a useful guide to help see Venus during the day.  I recommend using a program like Stellarium to help you out. Set it up for your location and time of observation. Be sure the Moon and Venus are up in the sky during the day. Note the position of Venus relative to the Moon. Now you are ready to track down Venus in broad daylight.

Find the Moon and slowly scan away from the Moon toward where Venus should be located according to Stellarium. You really have to look directly at Venus to see it during the day.  That is, the image of Venus must land on the fovea of your eye. The fovea is the small spot in the center of your retina where the cones are most closely spaced and your vision is most acute. Once you hit that spot, Venus will pop into view so prominently you will wonder how you missed it before.

It takes some practice.  Be sure your eyes are focused at infinity (focus on the Moon before you scan will do the trick). It also helps if you stand so the Sun is hidden Sun behind a tree or building to cut down on glare.

Many people wait until close to sunset to try this, but I have seen Venus practically any time it is up, even in the middle of the day. A good strategy might be to try it near sunset on Wednesday night and if you are successful, try it during the day on Thursday.

Happy observing!

January 25, 2012 Posted by | Astrophotography, Observing, Solar System | , | 1 Comment

Can You Spy Jupiter During the Day?

Other than the Sun and the Moon, it is challenging to see astronomical objects during the day. Venus is commonly seen during the day (and I will blog about it soon as it is becoming well positioned for daytime sightings). Jupiter is the other object that can occasionally be glimpsed during the day, but it is very challenging.

Fortunately, the Moon makes a close pass near Jupiter on January 2nd giving you a bit of help in this challenging observation. I recommend using a program such as Stellarium to make a finder chart for your particular location and time. Your best bet is late afternoon when the Moon and Jupiter have risen high enough in the east to make them easier to see. Here is a chart for Tucson at about 4pm tomorrow (the Moon moves about one Moon diameter per hour, so if you are observing several hours earlier or later, you might want to make a chart for yourself!)

Start by finding the Moon. You need to focus your eyes at infinity to have any chance of seeing Jupiter and the Moon is close enough to infinity that you can use it. Slowly scan toward the Jupiter. You have to look DIRECTLY at Jupiter to see it (that is Jupiter must be focused on the fovea, the center of your retina where you have the most sensitive vision) and it will pop into view. If you are off just a little bit, you won’t see it so this observation takes some patience! Some people find it is easier to wait until the Sun is almost going down, but I like the challenge of the fully illuminated sky!

It is much easier to take a pic of Jupiter during the day. Zoom in on the Moon (but not too far) and take a short exposure. Examine it closely on your computer screen to find Jupiter.

I have seen Jupiter during the day several times. It takes practice but is possible. If you are successful, you will join a fairly small and select group who have achieved this challenging observation.

January 2, 2012 Posted by | Daytime Astronomy, Observing, Solar System | 1 Comment