Cahall Observatory

Planetary Pairing December 2011

jformato — Tue, 27 Dec 2011 03:35:25 +0000

It can be tough to take pictures of the sky from the city, but with a little planning, clear skies and some equipment you can capture some nice shots. Tonight the thin waxing crescent Moon and Venus were close together in the southwest just after sunset. I set up my tripod, put on the telephoto lens and took a bunch of shots. I experimented with various ISO settings and exposure times so I could see the earthshine reflecting off of the unlit parts of the Moon’s surface. I set the lens to its maximum aperture so the depth of field would be as narrow as possible. Then the trees in the foreground would be far out of focus and would be less likely to block the pinpoint Venus. Lightroom was used to do some white balance adjustments, sharpening and cropping.

Summer astrophotography

jformato — Mon, 12 Sep 2011 21:30:51 +0000

30 second exposure of the Milky Way from the outer cape

This image was acquired with a simple digital camera placed lens-up on a driveway. I set the camera to ‘manual’ so I could control the shutter speed, which I set to 30 seconds. I also set the ISO to 800 so I could pick up the faint stars. When I imported the image to my computer it didn’t look like much, but there were lots of stars hidden in the details. I brought these out with the exposure slider, and this is the result. The dim glow in the background is the Milky Way, the hundreds of stars that are visible are nearby, in between us and the center of the galaxy. If I attempted this near a city like Boston, the whole sky would be a diffuse glow of scattered streetlights.

Parhelic arcs - around the full Moon!

We often see these on either side of the Sun here in the winter, but I have never seen these caused by moonlight. In order to pick up the faint colors in the arcs I had to completely overexpose the full moon, which is why none of the details are visible on its face. I stabilized the camera by placing it on the porch railing and shot for several seconds.

The arcs are part of a family of geometric patterns formed when sun or moonlight gets refracted by ice crystals in our upper atmosphere. This is a neat reminder that while it may be warm down here on Earths surface in the summertime, that it is always cold in the upper atmosphere! To learn more about atmospheric optics, check out this great page: http://www.atoptics.co.uk/

Outreach, 2010 – 2011

jformato — Thu, 28 Apr 2011 14:11:53 +0000

Yesterday we hosted an ‘Astronomy Fair’ at school. The twelfth-grade astronomy students prepared lessons and activities for 1st through 3rd graders from a local elementary school. Activities included observatory tours, planetarium shows, scale-modeling the solar system using the school’s large fields, and a science-fair type gathering in Alumni gym. Students experienced weight on different planets, did a ‘Where’s Waldo’ activity with a Saturn V rocket poster, played around with astronomy software on ipads and more. Attached is a slideshow.

This year we also hosted several boy and girl scout troops from around the South Shore, hosted students from Epiphany School in Boston and held a class for Braintree Adult Education.

Observing, Fall 2010

jformato — Fri, 29 Oct 2010 03:36:42 +0000

Jupiter is the main attraction in the evening sky this fall. Look southeast shortly after dark and there it is- a bright and steady yellow-white planetary light. Tonight we were lucky to catch the space station flying overhead as well. We looked at Jupiter through the telescope, and then placed a camera at the eyepiece and took some pictures.

This first picture is of Jupiter with four large moons. The large disk at the center is the planet, and the four points of light near it are the four ‘Galilean’ moons of Jupiter. Close together are Io and Europa, and on the other side are Callisto and Ganymede.

Jupiter and Four Moons, October 28 2010

The disc of the planet is so much brighter than the moon themselves that its next to impossible to take a picture of both together. The above exposure lasted a few seconds, while the exposure below was a fraction of a second. This short exposure makes it so we can’t see the moons, but we can see details on the ‘surface’ of Jupiter, namely tops of cloud bands. Note that there is only one equatorial cloud band (there were two for the past several decades).

Jupiter, high magnification, October 28, 2010

September Moon

jformato — Sat, 02 Oct 2010 00:48:32 +0000

Astronomy student Aaron A. was inspired by last month’s full Moon and captured it between the clouds with his point-and-shoot digital camera.

Click to view slideshow.

Extrasolar Planets: the ‘Goldilocks’ Zone

jformato — Fri, 01 Oct 2010 18:04:58 +0000

There has been a lot of excitement about this week’s announcement from the Keck observatory that a planet orbiting the star Gliese 581 is located within the ‘habitable zone’. Not too hot (too close to the parent star), not too cold (too far from the parent star) but just right temperature to potentially harbor conditions thought to be necessary to support the evolution of life.

That is the concept of the habitable zone in a nutshell, but the search for planets around other stars is more complex than that. You can experiment with various stars and planetary systems with this fun applet. Click the picture below- it will bring you to an interactive flash animation that will help you understand the ideas involved.

Planets in August 2010

jformato — Mon, 02 Aug 2010 12:12:11 +0000

There are some solar system happenings in the West after the sun sets this August. Things will be changing quickly from the start to the end of the month. If you have clear nights, go out about 30 minutes after sunset and watch for the following:

August 1st. Mercury is a challenge, low in the glow of Sunset. Venus is very bright, Mars and Saturn are grouped to the upper left of Venus.

Sunset, August 1, 2010.

On August 6, Venus, Mars and Saturn make a triangle.

August 6, 2010.

On August 13, the waxing crescent Moon joins. If your skies are cloudy that night, try on the 14th as well.

August 13, 2010.

On the 18th, Mars and Venus are quite close.

August 18, 2010.

At the end of the Month, Venus and the star Spica are in conjunction, while Mars and Saturn are fading away.

August 30, 2010.

Happy hunting!

An exploration of the Orion Nebula

jformato — Thu, 25 Mar 2010 13:44:43 +0000

I love these Hubblecasts. The originals are in high definition, and you can subscribe to the podcast in iTunes. Hubblecast 32.Born in Beauty: Proplyds in the Orion Nebula

Clyde Tombaugh on I’ve Got a Secret

jformato — Sat, 20 Feb 2010 16:40:08 +0000

An interesting look back into time.

Astronomy Software for iPhone

jformato — Sat, 20 Feb 2010 16:21:50 +0000

This week I downloaded the free iphone app ’3D Sun’ (App store link here). This application was written by the team at NASA who are also responsible for the spaceweather.com report, a webpage that tracks the Earth-Sun environment.

There is a huge amount of publicly available image data on our Sun, including real-time, three-dimensional video of the Sun at multiple ultraviolet wavelengths (thanks to the Stereo-A and Stereo-B satellites). This video is an example of dozens of time-lapse movies available at the website.

The iphone app ’3D Sun’ allows for direct, easy access to that data, and also provides alerts to your phone in the event of a big event on the Sun, such as a huge solar prominence erupting or a coronal mass ejection- useful for astronomy teachers in particular and solar physics enthusiasts in general. NASA is dedicated to making this data easily accessible, and this application is part of that work.

You can scroll around the Sun in three-dimensions, zoom in and out, and watch the Sun evolve over time. Along with the Mars and Moon Globe Apps (and of course Google Earth for iphone), 3D Sun adds nicely to the library of ‘three-dimensional data of solar system objects on my phone’. Waiting on the other planets now. Screenshots below.

From the Aurora Page

Info About the Stereo Spacecrafts

A 3-D, rotatable image of the Sun