April Moon at Apogee

 Our Moon reaches apogee, (greatest distance from Earth), on Saturday April 15th. At that time the Moon will more or less be at a distance of 31.78 Earth diameters (405,475 km or 251,950 miles) from the Earth.
   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 on graphic to see it larger   On the morning of the apogee Moon the 18-day old waning gibbous Moon rises a couple of hours before the Sun and is visible over the southern horizon.

   
   
   

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.

Uranus at Solar Conjunction

uranus-at-conjunction-from_earth
   Friday April 14th the outer planet Uranus will be at solar conjunction. This is a position where Uranus is on the opposite side of the Sun as seen from Earth. All of the planets, as viewed from Earth, will reach solar conjunction at some point during their orbit around the Sun. For the two inner planets, Mercury and Venus, this is known as superior conjunction rather then simply conjunction as it would be for the outer planets.

   
   
   

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.

Yuri’s Night 2017

yuri   April 12th 1961 Cosmonaut Yuri Gagarin became the first human to leave the surface of the Earth and orbit our planet. Coincidentally 20 years later, on the same date in 1981 the United States launched its first space shuttle, the Columbia. However April 12th is a date for celebrating the accomplishments of the Russian space program and the cosmonaut who became the first to orbit the Earth. So, on April 12th people around the world will take part in local events in what is known as Yuri’s Night. Use the link to the Yuri’s Night web site to learn more about this event and to see if there is a Yuri’s Night event in your area.

yuri   A few years ago during the 50th anniversary I had an opportunity to work with a group of musicians (Dark Matter) in producing a series of videos about the solar system and our home planet that were then projected as full-dome videos on a Planetarium dome ceiling. Accompanying the videos were two musicians playing their respective instruments (Flute and Clarinet) along with electronic notes, live sampling of their music, and sounds of the interior of a spacecraft. Below is a version of that performance that was entered into a worldwide contest – placed in the top five by the way.


   
   
   

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.

Full Moon Near Jupiter and Spica


   Monday evening April 10th the full Moon will be about 3o from Jupiter and about 5o from the blue-white star Spica in Virgo the Harvest Maiden as the trio rises in the east.

   
   
   
   
   
   

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.

Mercury Begins Retrograde Motion


   Sunday April 9th the innermost planet Mercury reaches a point in its orbit around the Sun where it moves toward the west as we view Mercury from the Earth. Typically when one hears this the term Retrograde Motion comes to mind, but with regard to an outer planet (relative to Earth). However while an outer planet’s retrograde motion is apparent the westward motion of an inner planet, Mercury or Venus, is very real. For Mercury or Venus retrograde motion begins around the time of eastern elongation and continues through inferior conjunction to around the time of western elongation. For Mercury this particular retrograde motion will end next month on the 17th.

   
   
   

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: 2017

Zooming in on Jupiter at Opposition   Friday April 7th, the outer giant 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 about 167o.
   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 like Jupiter at opposition, a full Moon rises at sunset, sets at sunrise and is visible all night.


   Jupiter rising with Spica.
   
   
   
   
   
   
   
   
   
   
   
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.

April Moon at Ascending Node

   Friday April 7th the 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 April 7th the 11-day old waxing gibbous Moon will rise with the constellation Leo the Lion and is located near the Lion’s tail, the star Denebola.

   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.