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The Vernal Equinox

Each year, the vernal equinox signals the beginning of spring (in the Northern hemisphere). So what determines the date of the vernal equinox?

Technically speaking, the vernal equinox occurs on the day when the Earth's axis (which is tilted by 23.5°) is pointed neither towards nor away from the Sun. The Sun will appear directly centered over the Earth's equator. Put simply, however, the length of the day and night are nearly equal, hence the term equinox. Therefore, after the vernal equinox, the days will be longer than the nights, signaling the beginning of spring. Typically the equinox occurs on March 20^th or 21^st.

Precession of the Equinoxes

The Earth's spin axis is not fixed in direction, however. It actually wobbles about its axis, much like a top. It takes our planet about 26,000 years to complete one "wobble". This has some interesting effects on the view from planet Earth. Not only will it eventually cause our beloved pole star, Polaris, to no longer remain stationary, but it also causes an effect known as the "precession of the equinoxes". This causes the point on the celestial sphere that the Sun occupies to move over the course of 26,000 years.

Lately, much ado has been made about this, as the Sun will soon appear to cross the galactic center on the winter solstice of 2012. This is pure superstition, however, and has no credible basis in real science (just see this post).

Balancing Eggs

Contrary to popular belief, it is not any easier to balance on egg on the equinox than it is on any other day of the year. If you try long enough, you can balance an egg on its end any time of year. It just happens to be that more people try it on the equinox than any other time, and so the myth perpetuates.

The following table lists some upcoming equinoxes.

• 2009 - March 20, 11:44 UTC


• 2010 - March 20, 17:32 UTC


• 2011 - March 20, 23:21 UTC


• 2012 - March 20, 05:14 UTC

Clear skies!

StarWalk Review: A Planetarium for the iPhone

For the high-tech crowd out there, a new iPhone app aims to put a planetarium on your phone! Star Walk, by Vito Technology, is a planetarium simulator that runs on the iPhone or iPod Touch and can be purchased at the iTunes App Store for $4.99. Recently, I was contacted by Vito Technologies about an evaluation version of the application. Although I don't personally own an iPhone, many of my friends do. Luckily for me, one friend let me borrow his iPhone for a few minutes to try out this new software. Below, I've written a review from the time I spent testing the software.

Features

First impressions are important in many things, and here, Star Walk did not let me down! The first thing you notice when you start this app is that it asks permission to find your current location. I guess this is commonplace in iPhone apps any more, but it surprised me how easy it was. I simply clicked "Yes" and the iPhone triangulated my position via cell signal and adjusted the star field accordingly. On the more advanced iPhone 3G, it uses GPS navigation to find your location for an even more accurate fix! Below, you can see the screenshot of this step, and it's approximation of my position. I'm in Youngstown, OH, so you can see that it is very accurate!



As cool as that was, Star Walk has more to offer. After completing the location setup, the star field comes up, in typical iPhone quality, full of color and smooth movements. Moving and rotating the star field is accomplished by dragging one finger across the screen, while zooming in and out utilizes the iPhone's Multi-Touch interface. Star Walk includes many objects, including the Messier catalog, planets, and meteor showers. Below you can see the interface. I have M39 highlighted to show that part of the interface. After a few minutes getting used to Multi-Touch (I'm not a native iPhone user) I found navigation to be quite easy and intuitive.



When you select an object, there is a button in the corner of the screen with an 'i' on it. Clicking this button gives you information on the object, as shown below demonstrated with Saturn. Star Walk has information such as this for everything that you can see in the display. The coolest thing I noticed here is that if you click the button with a 'w' on it, it takes you to the Wikipedia page for that object!



Also, you can change the current time using a touch-friendly interface. This is useful for simulating future and past events. This is especially useful when you want to, for example, figure out how much the Moon will interfere with the next meteor shower.



Star Walk also includes a "night mode" (shown below) that changes the screen to dim shades of red that preserves your night vision for use under the stars.

Conclusion

After only a few minutes testing this app, I would say it is a must have for amateur astronomers. The interface is easy to use and useful. The inclusion of a night mode is a serious plus for this software. Overall, Star Walk reminds me of a mobile version of Stellarium, albeit with better graphics and user interface. If I had an iPhone, I would definitely be purchasing this app, especially since it's so cheap at $4.99. The only thing that I found issue with in Star Walk is the fact that it doesn't render the positions of planets' moons. This would be a very valuable feature, and would hopefully be added in future versions. The other features of this program, however, are valuable enough to make this app a great buy!

In short, I recommend this app to all iPhone or iPod Touch users with a curiosity about the night sky!

Click here to download Star Walk from the iTunes App Store.

NOTE: I receive no compensation, monetary or otherwise, for the publishing of this review.

Clear skies!

Saturn - March 14, 2009

Tonight, I got my third night of clear skies in a row, which is a rarity in Ohio during the winter. So I spent most of the night observing Saturn, both with and without a #80A filter. I also spent some time on M51, the Owl Nebula, and Comet Lulin. Below is a sketch I made of Saturn tonight.

Saturn - March 14, 2009.

A Reader-Submitted Photo of Debris Re-Entry

The other day, a reader named Ferzeno from Jakarta, Indonesia sent me a photo he took on his way home from work. The picture shows an unknown re-entrant. Said Ferzeno:

"The sky was clear. It was just like a comet, with a bright long tail. I saw it at 05:57 PM [10:57 UTC] and took a picture from my cellphone... It traveled downward very fast."

Below, you can see the object in the center of the picture. Also beneath that, is a close-up of the unknown object. My best guess is that it was a piece of debris from the recent collision between Cosmos 2251 and Iridium 33. If anyone else saw this event or caught it in a photo, leave a comment below!

Unknown re-entrant captured by Ferzeno in Jakarta, Indonesia.
Image captured March 11^th, 2009 at 10:57 UTC.

Closeup view of re-entrant.

Clear skies!

Clear Skies For My Birthday

Again this year, the weather gave me a birthday present and a few hours of clear skies! They're already starting to cloud over, but at least I got some observing time in during spring break. I've been pretty busy working with our radio telescope, gathering data and working out any kinks I find along the way. Looks like we've got a noise floor issue to deal with before we move forward, but we maybe, just maybe, might have captured the Crab Nebula with the radio telescope.

You know you're a geek when you spend spring break working on a radio telescope!

Clear skies!

First Interferometry Data!

Today we mounted our interferometer to the roof of the engineering building and left it recording for a few hours while we went to Arby's. Below is the (noisy) data we captured. Although its incredibly noisy, it proves that the interferometry function is working properly and both amplifiers work well. Check it out below!



First interferometry data from Project Odin. Note the rise in signal strength on the bottom chart (the interferometry) near 22:00 (Time is incorrect, it was actually near noon local time). This corresponds to the time in which the Sun moved through our beam pattern! Note that because of RFI and short timespan, the typical fringes are missing.

Over the next week, we will be running the radio interferometer continuously, in a more radio-friendly environment. I can't wait to see the results!

Astronomy Calendar, March 2009

The following is a list of celestial events occuring during the month of March 2009:

• March 3 - The Moon is 0.8 degrees North of M45 (the Pleiades) at 08:00 UTC.


• March 8 - Saturn is at opposition. Opposition is the point where we are closest to Saturn, and thus it will be the best viewing time. Daylight Savings Time begins today. (I think we just need to get rid of DST, however). The Moon is 1.5 degrees South of M44 at 02:00 UTC.


• March 11 - Double Galilean shadow transit at 04:03 UTC.


• March 12 - My birthday! Maybe I'll get clear skies.


• March 16 - GLOBE at night campaign begins and runs until March 28.


• March 20 - Vernal Equinox occurs today.


• March 22 - Jupiter is 1.5 degrees South of the Moon.


• March 24 - Mars is 4 degrees South of the Moon.


• March 30 - The Moon is 0.6 degrees North of M45 (the Pleiades).

There are no major meteor showers in March.

If anything new develops, I'll update this list. Clear skies!

Best Images of Comet Lulin

Imaged by many astronomers, Comet Lulin may have been one of the most popular non-regular comets I've seen recently. There were so many great images I couldn't possibly include them all, so I've posted the best for your viewing below. Overall, I think Comet Lulin was a great way to kick off the International Year of Astronomy. If you didn't get to see the Comet, just check out these beautiful pictures of the popular green comet! If your image isn't on the list, and you'd like to see it here, just submit your image to me at sean@visualastronomy.com or post a comment below!

This first image is actually an animation. Click the image above to see an animation of Comet Lulin moving across the sky. This is REALLY cool, I'd suggest taking a peek! (Image is 10 MB) Courtesy of Hiro.

Courtesy of James Champagne.

Courtesy of James Champagne.

Courtesy of James Champagne.

Courtesy of Burley Packwood via West Seattle Weisenheimer.

Courtesy of Mike Broussard.

Courtesy of Mike Broussard.

Courtesy of John Wohlfeil.

Of course, as a visual observer, I've got to include at least one sketch! Courtesy of Jeremy Perez.

Comet Lulin caught with a DSLR and 30 sec. exposure. Courtesy of Tavi Greiner.

Courtesy of Myron Almond.

There are also excellent conversations on Comet Lulin at Cloudy Nights and SLOOH.

Clear skies!

Video of NEO Asteroid 2009 DD45

Today, March 2, 2009, a Near Earth Object known as Asteroid 2009 DD45 made a close pass to Earth. Asteroid 2009 DD45 passed within 63,500 km (~39,000 miles), or about 0.17 Lunar orbits. Below is a video of the NEO Asteroid 2009 DD45. The video is in real-time, and you can see the asteroid as a white speck that floats from right to left.

(Some feed readers may require you to follow the link to the actual page)

Sending Earth-Life to Phobos?

In the near future, the Russian space agency and the Planetary Society will be sending samples of life to the Martian moon, Phobos. The mission, known as Phobos-Grunt, aims to send several different types of Earth-life to the barren moon of Mars. The Planetary Society will be sending 10 life forms in its cargo. These include tardigrades (or water bears), various plant seeds, and bacteria cultures. The Russians are sending more complex life, also, including some crustaceans, mosquitoes, and fungi. The Russians have already tested whether a mosquito can survive in space (they can).

The purpose behind this mission is to determine the effects of long-term space travel on biological systems. Lessons learned here may affect future plans for human flights to Mars or beyond. The Phobos-Grunt mission, isn't a one-way suicide mission, however. The samples will be returned to Earth for observation and testing. Also, this mission is intended to be an example of "reverse panspermia", if you will. By determining whether life can survive long-term exposure to radiation and temperature variations, this mission can give us insights into the possibility of panspermia (life originating on Earth via microbes arriving on meteorites).

This seems to fly in the face of typical spaceflight practices, however. Typically, a spacecraft not carrying humans is sanitized of all life forms before launch, to prevent an accidental spread of Earth life to other planets. Now, we're purposely sending our life forms to, in this case, a nearby planet's moon. While there wouldn't be any life to disturb on this airless moon, what are the ethics of sending Earth life to space? Can we ethically plant life on other planets? If so, what checks do we need to execute to ensure we don't destroy something that was already there? Needless to say, since Phobos has no atmosphere, the chances of life ever procreating there are about zero. As such, its not a really big deal for us to even leave life there. If, however, these organisms return from their trip, it might be strong evidence to the possibility of panspermia.

What do you think?