Two ISS Midwest Flyovers

   Approximately every 90 minutes the International Space Station (ISS) completes an orbit around the Earth. At the correct times, around sunset and sunrise, the large solar panels on the ISS reflect sunlight downward toward the Earth’s surface. Depending on the orientation of the solar panels and where you are you may be able to see the reflected sunlight off the solar panels. To the naked eye the ISS may appear as bright as Venus, around a -4 apparent magnitude.
   This evening, March 21st and tomorrow evening the 22nd the ISS will be visible, weather permitting, as it passes over the midwest United States. Use the links below to see visibility opportunities for your location.

   The ISS travels in excess of 17,000 miles per hour and it takes maybe 6 minutes or so to cross the United States from west to east.

   Two excellent websites for ISS viewing information are below. You will need to input your location information at both sites.

   ISS Sightings
   At the NASA web site you will get a list of the next several dates and times for viewing the ISS that includes it’s rising and setting times and directions of travel (always west to east), and some other information. Pay attention to the maximum altitude and length of time above the horizon.

   Heavens Above
   The Heavens Above website provides a list of viewing opportunities like the NASA web site but in addition you may see a star map showing the ISS path across the starry sky. You will find that this web site has quite a lot to offer with viewing information ranging from the ISS to Iridium satellites and other satellites, planet information, and so on. Well worth bookmarking.

   
   
   

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.


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Waning Gibbous Moon Passes Spica

   Over the next 2 days, March 21st and 22nd, the waning gibbous Moon will be passing by the blue-white star Spica in the constellation Virgo the Harvest Maiden, coming within 6-7o on the 21st and 10-11o on the 22nd.
   From the mythology about Virgo she is often depicted with a bundle of grasses, like wheat, clutched in her left hand. The star Spica represents that bundle.


   
   
   

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.


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Martian Spring Equinox

A Martian Year

A Martian Year – at One Earth Month Intervals

   Saturday March 23rd is the spring equinox on the planet Mars as the planet transitions from its winter season to spring 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. Each seasonal start/ending point is 90 degrees apart, but because of its elliptical-shaped orbit each Martian season is of varying lengths.

   I’m not exactly sure why this particular date is used but by international agreement astronomers have selected April 11th, 1955 as 0 degrees for year 1 of this Martian calendar. What this works out to is that on Saturday March 23rd, Earth time, it is the start of spring for year 35 using the aforementioned calendar system.

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 Explore the Moon to Mars website.

   
   
   

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.


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2019 March Equinox

   Wednesday March 20th is an equinox day. This means that for those in the northern hemisphere winter is ending and spring has ‘sprung’ (starts). For our counterparts south of the equator summer is ending and fall is beginning. From a geographical perspective we would describe the Sun as being over the Earth’s equator, and as this graphic shows there would be an equal amount of daylight and night on our planet as a result.
    At mid-day on the equator the sun is directly overhead and from that latitude you have no elongated shadow, just a ‘blob-like’ shadow at your feet as this picture of my feet taken at mid-day in Quito Ecuador shows.

    Regardless of your hemispheric preference get outside and cast a shadow!

  Northern hemisphere spring officially (well at least astronomically) begins at 22:01 UT on the 20th (5:01 pm CDT) when the Sun reaches the celestial coordinates of 0 hours and 0 degrees as it moves northward along the ecliptic crossing the celestial equator. At this location the Sun is just within the constellation of Pisces the Fishes and not entering Aries the Ram as the pseudoscience of astrology would have you believe.

    To learn more about the celestial coordinates click here to read a previous post about seasons and the equinox.

   Click here to see the online world sunlight map used to make the day/night graphic at the top of the page.


   Celebrate Solar Week March 18th-22nd. Click here to go to the Solar Week web site.

   
   
   
   During a trip to Quito Ecuador to visit one of the exchange student we had hosted, and her family, we spent the day at a Museum on the equator, Mitad del Mundo. I brought along my over-sized protractor knowing in advance that we would be at the museum. So at mid-day I had my wife stand on the equator (yellow line) and hold a string to the top of her head while Cathy, a sister of our exchange student, held the protractor. This was done during the summer so the Sun was over the northern horizon at mid-day and the Sun’s angle above the northern horizon was around 75o.

   Here is a short series of hourly pictures taken during the day on the September equinox on the equator in Quito Ecuador at Collegio Menor San Francisco de Quito, a private school that I visited and did the SunShIP project with (Sun Shadow Investigation Project).

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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.

March Moon at Perigee

   Our Moon reaches perigee, (closest distance to Earth), for this orbit, on Tuesday March 19th. At that time the Moon will be at a distance of 28.17 Earth diameters (223,309 miles – 359,381 km) from the Earth.

   The 13-day old nearly full, waxing gibbous, Moon rises shortly after sunset local time is visible all night. Over the southwestern horizon, as the Moon is rising,is the planet Mars which sets around midnight.

   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

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.


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Moon – Regulus Conjunction

   Monday evening March 18th the 12-day old waxing gibbous Moon will be about 1o from the star Regulus, the ‘heart’ of Leo the Lion. Both will very easily fit within the field of view of binoculars.

   
   
   

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.


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March Moon at Ascending Node

   Saturday March 16th the 10-day old waxing gibbous Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.

   On the day of the node crossing the 10-day old waxing gibbous Moon rises during the mid-afternoon and sets about 2 hours before sunrise on Sunday.

   Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

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.


Also Follow me and other great resources at Feedspot.