It’s All About Exposure

   Last night after sunset I set out to try and capture a picture of Venus less then 1o from the open star cluster M-35, near the feet of the Gemini Twins. Additionally the first quarter Moon was within about 1.5o from the star Regulus, the ‘heart’ of Leo the Lion, and also easily seen as the bottom of the backward question shape this constellation is best known for. Since my western skies are illuminated by the lights from an athletic field, and the eastern suburbs of Kansas City, MO. the limiting magnitude is around 2 or 3, meaning that the dimmest stars easily seen in that direction have to be at least 3rd magnitude or brighter. So with that in mind I took over 60 pictures with various camera settings but the skies were just too bright to capture the light from the stars making up M-35.

   Then I turned my attention to the Moon and Regulus. Regulus was close enough to the Moon that it’s light was nearly washed out by the Moon’s reflected Sun light. The difficulty of catching both has to do with camera settings. For example opening the shutter and increasing the exposure time washes out the Moon but allows Regulus to be seen.
   I use a Cannon Rebel EOS T7i with a touch screen allowing me to change settings very easily and see the effect in the change in real time.
   Camera settings: 300 mm; f/13; 1/40 sec.; ISO-400


   For this picture I increased the exposure time but left the other settings as they were. The Moon is larger in this picture because I zoomed in on the original before cropping it for this blog.
   Camera settings: 200 mm; f/13; 5 sec.; ISO-400

   
   
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

It’s the Autumn Equinox on Mars

   Tuesday May 22nd is the autumnal equinox on the planet Mars as the planet transitions from summer during its 684 Earth day orbit around the Sun.
   Seasons on Mars are marked by the planet’s heliocentric longitude coordinates using the position of Mars along its orbit around the Sun. At the Martian spring equinox Mars is at 0o longitude.
   Each seasonal start/ending point is 90 degrees apart, but because of an elliptical-shaped orbit each Martian season is of varying lengths. Mars is at its greatest distance from the Sun, aphelion, before it reaches the Martian summer solstice when Mars is at 70o longitude. Perihelion, its closest to the Sun, is when Mars is at 250o longitude.
   Eccentricity of Mars and Earth for comparison.
Mars: 0.0934 – Earth: 0.0167

   I’m not exactly sure why this particular date is used but by international agreement astronomers have selected 11 April, 1955 as 0 degrees for year 1 of this Martian calendar. What this means is that on Tuesday May 22nd, Earth time, it is the start of autumn of year 34 using the aforementioned calendar system.

Year 34
0 degrees — Spring Equinox — May 05 2017
90 degrees — Summer solstice — November 20 2017
180 degrees — Fall Equinox — May 22 2018
270 degrees — Winter Solstice — October 16 2018

Year 35
0 degrees — Spring Equinox — March 23 2019
90 degrees — Summer solstice — October 08 2019
180 degrees — Fall Equinox — April 08 2020
270 degrees — Winter Solstice — September 02 2020

Year 36
0 degrees — Spring Equinox — February 07 2021
90 degrees — Summer solstice — August 25 2021
180 degrees — Fall Equinox — February 24 2022
270 degrees — Winter Solstice — July 21 2022

   Learn a little (or a lot) more about the exploration of Mars at the NASA Journey to Mars web site.

   Learn a little (or a lot) more about Mars at the NASA/JPL Mars Curiosity mission web site.
   Or read about the InSight mission currently on its way to Mars.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

Sun Not Really in Gemini

  According to the pseudoscience of astrology the Sun enters the constellation of the Gemini Twins on Monday May 21st. When in fact the actual position of the Sun on this date is still within the boundary of the constellation of Taurus the Bull, as this graphic and the banner graphic show.

   Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.
   
   
   

   
   
   

Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Sun Enters Taurus

view-from-earth-may   Monday May 14th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation Aries the Ram and into the constellation of Taurus the Bull. This is the true or actual position of the Sun as opposed to the pseudoscience of astrology which usually has the astrological Sun one constellation ahead or east from the Astronomical Sun’s position.
   
   
   
   
   Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Jupiter at Opposition- 2018

Zooming in on Jupiter at Opposition   Wednesday May 9th at 0 UT, (Tuesday May 8th at 7 pm CDT), the outer giant ringed planet Jupiter reaches the point in its orbit around the Sun that places the Earth in between Jupiter and the Sun. This is known as opposition, and opposition is an orbital position that applies to solar system objects (outer planets, dwarf planets, asteroids, comets, etc.) orbiting the Sun beyond the Earth’s orbit. An object at opposition will have approximately the same heliocentric longitude as the Earth’s heliocentric longitude. So on Tuesday both planets will have a heliocentric longitude of around 228o.
   An opposition of Jupiter occurs approximately every 13 months because both Earth and Jupiter are moving. After one Earth Revolution, an Earth year, the planet Earth will be where it was the previous year at opposition with Jupiter. However Jupiter will not be there because it has moved during the past year as well. It will take the Earth about an extra month or so to catch up with Jupiter. Earth moves 360o each year while Jupiter moves approximately 12o each Earth year.
Sunset Local Time Sunset Local Time.
   When an object is at opposition it rises at approximately the same time as local sunset and that same object at opposition sets at approximately the time of local sunrise. In other words an object at opposition will be up all night from sunrise to sunset.
   Picture our Moon at full phase and how it is directly opposite the Sun, with the Earth in between. The full Moon in effect is at opposition but we call it the full Moon instead. And so both the full Moon and Jupiter at opposition, rise at sunset, set at sunrise, and both will be visible all night.

   
   
Take a brief tour of the Jovian (Jupiter) system. Music by Dark Matter.
Live recording of music written by Richard Johnson. Video by me!

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Minor Planet, Asteroid 4 Vesta at Opposition

   Wednesday 9 May the minor planet, Asteroid 4 Vesta will be at its perihelion for this orbit. Perihelion is when a solar orbiting object is at its minimum distance, or closest to the Sun. Asteroid 4 Vesta is one of the largest main belt asteroids with a diameter of about 525 km (326 miles).

   At this perihelion 4 Vesta will be 2.1517 AU (321,889,738 km; 200,013,010 miles) from the Sun. At this distance 4 Vesta will reach an apparent magnitude of around 6.0 meaning that it could be visible using binoculars. 4 Vesta lies within the region of the Milky Way and about 1o from 4 Vesta is the Omega Nebula, M-17 (apparent magnitude 7.0), and around 4o from 4 Vesta is the Eagle Nebula, M-16 (apparent magnitude 6.5).

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Sun Not in astrological Sign of Taurus

April 20th According to the pseudoscience of astrology the Sun enters the constellation of Taurus the Bull on Friday April 20th. When in fact the actual position of the Sun on the 19th is still within the boundary of the constellation of Aries the Ram, as this graphic shows. Actually the Sun had just entered Aries the day before on April 19th.

Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.


Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.