Use the Solar Observatory to See the Pleadeas In Daytime

The lovely Pleiades  star cluster is not visible in our nighttime sky, because it’s lost in the glare of the Sun.  But it’s fun to look for it while it moves past the Sun in our skies.  And we can do that with the SOHO solar telescope.  SOHO (Solar & Heliospheric Observatory) is a joint USA and European Space Agency space mission to study our star.

SOHO has special cameras, some of which block out the Sun so we can see the Sun’s outer atmosphere and how the Sun’s magnetic field affects it.  SOHO blocks out the Sun so well, we can see stars and planets passing through the glare of the Sun.

Check this week and watch the Pleiades, that star cluster that looks like a little dipper, or nameplates on older Subaru cars, pass through the view of the C3 camera .  Here’s a sample from yesterday:

latest 2016 05 15 2042

The Pleiades are in the upper left of this scene and will move to the lower right this week. The incredibly bright object on the right is the planet Venus.

Here’s a movie of the past three days, showing the Sun moving in front of the star field and Venus racing to keep up.

current_c3 05 15 1500.gif

Watching a tiny dot on the Sun

May 9th – the Transit of Mercury across the Sun.  I couldn’t see the last one, several years ago, since the sun was so dimmed by haze, after the solar filter, there was no sunlight left.
The sun broke through the stratocumulus clouds about 7:10am and I used my 8-inch dobsonian reflector telescope to watch Mercury move onto the solar disk. Because of turbulence and thermals, the edge of the sun looked very wavy, as if the sun had a scalloped edge.  Mercury seemed to stay attached to the edge of the sun for a long time, well after the entire disk was in front of the sun.
I took a few photos with my Canon XS camera in place of an eyepiece (‘prime focus’) and a white light solar filter (see below).

Mercury in that tiny dot in front of the Sun in this Canon XS camera exposure at prime focus 1/125 second exposure at ISO 400.

Then I drove to work with my 60mm f/11 Orion refractor. I was surprised I didn’t have to convince security that it was ‘take our telescope to work day’.  Viewing diagonally through the laminated glass and various thicknesses of cirrus clouds was difficult, since the sun was getting high in the sky by 10:30.  I found the best way to see a faint impression of the sunspot group and Mercury was to project the image of the sun onto a white sheet of paper tacked up on a partition in shade – something hard to do outdoors.  The 25mm (low power) eyepiece was best, but contrast and resolution was poor. By noon, a layer of altostratus clouds moved in from the south and covered the sky where the sun was, ending our viewing.
While I drove to work, it was fun to hear the FM stations talk about the transit.  WCBS-FM’s morning show host was complaining his co-hosts were very quiet, ‘looking at a tiny dot on a computer screen’, because they were fascinated by NASA and’s coverage of the transit.
PS I’ve done astronomy through the glass at work before. We’ve observed the Moon, a comet and last December, the Moon next to Venus.  IMG_0732 crop blue
 Click to see Venus as the dot to the upper left of the Moon. Dec 7 2015 250mm Canon XS 1/640 second exposure at f/11 and ISO 400.

Mercury and Venus in the SOHO Solar Observatory

As Mercury moves toward its passage across the Sun on Monday*, it was visible on the SOHO C3 camera.  The C3 is on the SOHO spacecraft, which watches the Sun from it’s post a million miles out from Earth.  The C3 has a shade to block out the Sun so it can see the Sun’s outer atmosphere.  It can also see stars in the background and the occasional planet that photobombs the scene.

This month, Mercury moved in from the left side of the C3 scene, dimming as the sunlight side turns away from us. Now you can’t even see it.  Venus is coming in from the right side, on the far side of the Sun, far away but still very bright.  The glare from Venus overloads the sensor and makes a big ‘splash’ on the sensor.

mercury and venus may 2016 soho

Follow the path of Mercury on this movie of recent photos from the C3 camera. The bright streaks are where the Sun’s magnetic field heats up the Sun’s outer atmosphere.  The ‘puffs’ emitted from are coronal mass ejections from the Sun.

current_c3 movie

Mercury is the tiny dot on the left moving a bit faster than the background stars (roughly on the path on the still photo above).


* Don’t view the Sun without a proper solar filter, firmly fixed to the open end of the telescope.  See Sky and Telescope, or our Westchester Astronomers newsletter for details on the Transit of Mercury across the Sun.


High tides from an invisible moon

The new moon on the Friday the 6th is near the time the moon is closest to us.  The combined effect of the line up of the sun and moon and the moon being closer than normal enhances the range of tides.  This new moon we can’t see induces large-than-normal tidal ranges from the 6th through the 9th.  (See the NYC NWS office to see if this sun/moon alignment and lunar perigee will produce coastal flooding.)

Conversely, the moon is farthest away this month near the time of full moon – furthest full moon this year.  Thus, May will have the smallest-looking Full Moon of 2016. If the largest full Moon on November 14 is a ‘supermoon’, is the smallest full Moon on the 21st a ‘minimoon’?  Photos taken with the same camera and settings at the same time of night can show a slight, but noticeable, difference in size.

Lonely in the morning?

Lately, it’s been darker and a bit more depressing in the morning since we went to ‘Daylight Time’.  But you have friends in the sky ready to cheer you every clear morning.  Look out to the south* -there are two bright dots in the sky – Saturn and Mars.  I’ve seen them as late as 6:15am in the dawn sky.  Saturn and Mars are about a hand’s width apart, and about the same distance above similarly bright star, Antares.


Take a look at the southern sky on your way to work – look for the color difference between Saturn and Mars.  Does Antares live up to its reputation as the ‘rival of Mars’? Check them out while waiting for your train or elevated subway or bus.

In a telescope at more than 30 or 40 power, Saturn’s rings are visible. At the same power, Mars is still a tiny reddish dot, appearing smaller than Saturn in a telescope.  Sometimes Mars has some darker surface features.

*South is a right turn from where the sun rises these spring morning.

More warm records than cold record temperatures

Check out the records at the National Climatic Data Center!

They have a web site that counts how many high and low temperature records have been set.  More high temperature records have been set than cold record temperature records in the USA in the last several years.

For example, so far in 2016, 1290 daily record high temperatures have been broken in the USA. During that same time, 239 record cold temperatures have been broken. This weekend will add many for cold records, but go to the website to see the number of hot and cold records broken over the past 12 months!

Record cold this weekend? Doesn’t happen much any more.

The National Weather Service is pointing out the intense cold snap coming our way this weekend.

Here’s forecast map of temperatures a mile up (850mb pressure height) in the atmosphere for Saturday night.  If we were to bring these temperatures down to the surface, warming as its pressure increases, our surface temperature wouldn’t be above 5 degrees Fahrenheit.


850mb heights and temperatures (degrees C) 10pm Sat Feb 13 (03GMT Sun Feb 14) Notice -30 deg C in the northeast US (1 mile up). Good luck finding a colder place.

But this air won’t be sticking around long enough to give us more than a few days of record-setting cold weather.  Here’s the forecast discussion from the NYC NWS….


                 FOR 2/14                    FOR 2/14

NYC...........2 (1916)  /  1.............17 (1979) / 19
LGA...........1 (1979)  /  2.............15 (1979) / 19
JFK...........4 (1979)  /  2.............17 (1979) / 19
ISP...........7 (2015)  /  1.............26 (1987) / 18
EWR...........0 (1979)  /  0.............15 (1979) / 19
BDR...........3 (2015*) /  0.............18 (1979) / 17

*IN 1979 AS WELL

Next post will show how many low and high records the USA had recently.