July 31, 2012

Take your own trip to Mars!

As Curiosity, the Mars Science Laboratory makes its final appoach to the “Red Planet” this week you can take your own trip to Mars and Saturn from your backyard.

Go out around 9:30 pm, or as soon as dusk has fallen. You’ll need a clear view to the southwest. Look for an equilateral triangle containing three “stars” above the southwestern horizon.

The rusty colored “star” to the right is Mars. To the left of Mars yellowish Saturn glows above sparkling Spica the only star in the trio. The planets and star form a triangle about 5 degrees across which you should be able to cover with your fist at arm’s length.

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You’re seeing Mars as it was 13 minutes ago and Saturn about 2 hours ago. That’s the light time to our solar system neighbors. Spica is a bit further away, 275 light years to be exact. The photons that reach your eyes from Spica tonight left the star in 1737. Ben Franklin was 31, John Adams was a toddler of 2 and it would be six years before the birth of Thomas Jefferson. Galileo’s body was moved to the church of Santa Croce in Florence, Italy in 1737 nearly a century after his death. Click the map to enlarge

Spica, the “Alpha” star in constellation Virgo lies on the far side of our spiral arm of the Milky Way.

I made the map image with John Walker’s Your Sky. It shows the southwestern horizon at 10 pm local time the first week of August

Here’s a NASA video you may find helpful.

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July 24, 2012

Morning Dance

This summer’s beautiful morning dance starring planets Jupiter and Venus continues. If you haven’t yet done so I urge you to venture out before sunrise and glimpse the pairing.

Saturday morning, 21 July, I made an appointment with myself to go out and watch a visible pass of the International Space Station. ISS was to make an appearance over my location in southern Indiana at about 4:50 AM local time.

I decided to set up a camera to capture ISS streaking across my sky to the southeast.

I was out with the tripod and camera set up by 4:30 a.m. A cold front had moved through the area about 36 hours earlier and seeing was pretty good.

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Once outside I was struck by how beautiful Jupiter and Venus were above the eastern horizon, so I snapped a couple of images.

Image above left, Jupiter above and Venus below. Between and just right of the planets red giant Aldeberan is the “eye” of Taurus the bull in the V shaped Hyades star cluster. Click to enlarge

Then I began considering where ISS track would pass relative to the planets. I took an educated guess and decided I would try to capture an image of ISS cruising “near” the planets. 

jupiter-venus-iss-21-jul-12-4.JPG 

Image above left: The faint streak just left of center is the track of ISS. Right of ISS the Pleiades (Messier 45) or “Seven Sisters” star cluster, planet Jupiter and the Hyades cluster. Above left of the track is constellation Perseus.

Jupiter is rising around 2 a.m. and Venus about 3 a.m. The two planets are separating and will be nearly 40 degrees apart by the end of August. Venus will put on one of the two highest morning apparitions of its 8 year cycle in mid-August. For a few days centered around August 16th tiny Mercury will join the morning show. You’ll need binos or a telescope to spot Mercury below and left of Venus. To help locate Mercury trace an imaginary line from Jupiter through Venus and on down to Mercury.

Next: The Persied meteors and Venus does an afternoon disappearing act

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July 15, 2012

Sunspot 1520 is a BIG ONE!

About a week ago I started seeing comments on the astronomy blogs I watch about a “huge” sunspot. This solar storm was designated AR(Active Region)1520. On Thursday, July 12, 1520 was in the center of the Sun’s disc and “aimed” toward Earth. At about 15 hours UT AR 1520 released an X1 class flare and coronal mass ejection toward Earth. My lead post (above) covers that story.

In spite of the miserable heat and humidity here in southern Indiana this weekend I decided I wanted to take a look at the sunspot before it scurried around the Sun’s limb. Wanting to keep set up low tech and simple I opted to use easiest method possible. So, the choice was my $20 Galileoscope refractor set up in projection mode.

After 20 sweaty minutes I was observing the Sun’s disc projected into a cardboard box outfitted with a white piece of paper for a screen.

The reports were right. 1520 is a HUGE sunspot. It is probably at least 10 Earth diameters wide.

sunspot-ar-1520-15-jul-12-4.JPG So here’s an image. 1520 and AR 1518 and 19 can be seen at about 7 o’clock on the solar disc. Nothing fancy, remember this image was taken with a simple refractor and cardboard box! This image is the best of the bunch and you can see the edge of the paper “screen” and cardboard box. Click image to enlarge

Here’s a shot of my simple setup

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Remember, never look directly at the Sun. Severe eye damage will result!

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July 13, 2012

Weekend Aurora Alert!

A very large sunspot group, AR 1520, unleashed an X 1.4 solar flare directly toward Earth on Thursday, 12 July.

031011-aurora-341px.png The plasma from this flare and coronal mass ejection will arrive at our little blue orb at around 9:00 UT (5 am EDT) Saturday morning. Visible auroral conditions as far south as the mid-latitudes (think the U.S. midwest) and as far south as Alabama are possible. Image left: NASA

 Sunspot group AR 1520 is reportedly very large. I have heard the sunspot group  is visible without optical aid (ie, naked eye). DO NOT LOOK DIRECTLY AT THE SUN. PERMANENT EYE DAMAGE WILL RESULT IN AN INSTANT. OBSERVE THE SUN ONLY WITH APPROPRIATE FULL APERATURE FILTERS OR BY THE PROJECTION METHOD.

Watch the skies Friday and Saturday night. Best viewing will be in areas which are not heavily light polluted. Aurora is very diffuse and dim at mid lattitudes. For the latest detailed information check SpaceWeather or the Geophysical Institute websites.

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July 2, 2012

A Busy Week!

THE LOW FULL MOON…

Tuesday, 3 July, is a full moon, the night of the Thunder or Hay moon. This year’s Thunder moon will also be the “lowest” moon in the sky. What do I mean by “low” moon?

Head outside around 10 to 11 pm or later and note how low the Moon is off the southern horizon. The full moon nearest summer solstice is the “lowest” moon of the year in the northern hemisphere. The opposite is true for those south of the equator.

Why is this so? Let’s get some terms straight. The ECLIPTIC is the Sun’s apparent path across the sky. Professor James Kaler at the University of Illinois offers an excellent explanation here. The ecliptic can also be thought of as the “plane” of the solar system. The planets of our solar system and the Moon appear within a few degrees of the ecliptic in our sky. Think of the ecliptic as a great looping see-saw in the sky.

ecliptic-solstice.jpg

Earth’s axis is tilted 23.4 degrees to the plane of our orbit. As we circle the Sun we tilt toward (summer) or away (winter) from the Sun. This tilt also determines how the ecliptic cuts across the sky as viewed here on Earth. In the northern hemisphere summers the Sun tracks high across the sky. 

Look at the point on the chart labeled “summer solstice”. That is right about where the Sun is these days….but it’s already “heading south for the winter.”  When the Moon is “full” it is opposite the Sun in our view and on the lower side of the “see saw”at the spot marked “winter solstice”. In northern summers while the Sun is arcing high across the sky, at full phase the Moon is on the low side. If you happen to be in the southern hemisphere the opposite is true. The full Moon of July will appear high in your sky while the Sun rides low not far above your horizon. Check it out for me and let me know what you see!

Check this for yourself by going outdoors around mid-day and noting the position of the Sun off the southern horizon. NEVER LOOK DIRECTLY AT THE SUN! Do the same thing late in the evening with the Moon.

These early summer evenings are also a good time to check out the Moon illusion

WE’RE FURTHEST FROM THE SUN! WHY IS IT SO HOT?!!!

Thursday, 5 July at about 03 hours Universal time ( 11 pm EDT 4 July) planet Earth will be a aphelion, furthest from the Sun. We’ll be about 1.017 astronomical units from old Sol, roughly 152 million kilometers from our star or about 3.4% further away than at perihelion which happens on 3 January. Here in the midwest we have been suffering through nearly a week of high temperatures above 100 F so my saying we’re furthest from the Sun may seem crazy, but it is true. Our distance from the Sun varies because Earth’s orbit is ever so slightly elliptical.

The reason for the seasons is something I mentioned above, the tilt of Earth’s axis toward or away from the Sun. We’re having Summer now in the northern hemisphere because we’re leaning over toward the Sun. Those in the southern hemisphere are into winter and tilted away from the Sun. The seasonal changes have very little to do with the Sun’s distance.

Have an astronomy or stargazing question? Email the StarGeezer.

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