SpaceWatchtower: June 2022

Wednesday, June 22, 2022

Beautiful Pre-Dawn Planetary Alignment Thur.-Sat.

Illustration image

This graphic shows the pre-dawn alignment of the classical planets, to be seen in the United States just before Sunrise 2022 June 23 to 25. (Graphic Source: TimeandDate.com)

By Glenn A. Walsh

Reporting for SpaceWatchtower

A beautiful alignment of the classical planets will be visible in the early morning sky, just before Sunrise, at the end of this week (weather-permitting). The non-profit group, Astronomers Without Borders, has voted this planetary alignment one of their top “Sky Events” for this year!

In the early morning hours, Thursday through Saturday, the classical planets known throughout human history will be visible, in their actual order from the Sun.

The classical planets, the “wanderers” in the Earth's sky, are the planets, plus the Sun and Moon, observed via the unaided or naked-eyes (one-power) by our ancestors for millenia. These planets were observed long before there was any written history or other documents. And, of course, long before famous Italian astronomer Galileo Galilei observed planets with his first astronomical telescope in January of 1610 (coincidentally, it was June 22 in 1633 when Galileo was sentenced to house-arrest for the rest of his life, due to his published scientific papers, by the Palace of the Holy Office in Rome). Hence, no one knows who first discovered these planets.

These planets, which will be seen in order rise east-to-southeast from the horizon: Mercury, Venus, Mars, Jupiter, and Saturn (their actual order of distance from the Sun). The ancients also placed the Sun and Moon in the wanderer category. The ancients observed that these celestial bodies did not act the same as the other stars in the sky.

While all other “fixed” stars and constellations in the sky moved together, harmoniously, across the sky each night, these five planets, along with the Sun and Moon, wandered throughout the sky. Hence, they were termed the wanderers or wandering stars. The word planet is derived from the Greek word planetes, which means wanderer.

While the alignment will look near-perfect to observers on Earth, this is actually an illusion of perspective. While the planets will be the correct order, from their distance from the Sun, they would not appear as such an alignment if the observer was in Outer Space or on another planet.

The best time to view this alignment will be about 45-to-60 minutes before local Sunrise. Mercury, the smallest classical planet, will be the most difficult to spot. Mercury is always seen close to the Sun, because it is the closest planet to the Sun.

At peak altitude above the horizon, Mercury will only reach a maximum of 14 degrees above the horizon. So, Mercury will be tricky to find. If you cannot find Mercury one morning, simply try a little earlier the next morning.

And, because Mercury is so low in the sky, people in locations further north than the northern part of the United States, such as in Toronto or London, may not be able to find Mercury.

These five planets may still be visible for another week or so, beyond this week. However, the alignment may not be as impressive, as the planets move apart.

Mercury may be visible a few days into the new month of July. However, on July 16 Mercury will move into Superior Conjunction, when Mercury moves very close to the Sun (from an observer's perspective) and on the opposite side of the Solar System from Earth. At that time, Mercury is not visible at all.

UNLESS YOU HAVE THE PROPER TRAINING, NEVER USE BINOCULARS OR A TELESCOPE TO TRY TO FIND MERCURY. SHOULD THE SUN RISE UNEXPECTEDLY, AND ENTER YOUR TELESCOPE OR BINOCULARS, IT COULD CAUSE PERMANENT EYE DAMAGE TO THE OBSERVER!!!

Internet Links to Additional Information ---

Classical Planets: Link >>> https://en.wikipedia.org/wiki/Classical_planet

Superior Conjunction: Link >>> https://en.wikipedia.org/wiki/Conjunction_(astronomy)#Superior_and_inferior

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeis

Wednesday, 2022 June 22.

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gaw

Glenn A. Walsh, Informal Science Educator & Communicator (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>> http://www.planetarium.cc Buhl Observatory: Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

Sunday, June 19, 2022

Summer Begins at Solstice Early Tuesday

[Graphic Source: © Copyright 2005, Eric G. Canali, former Floor Operations Manager of the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center - Pittsburgh's science and technology museum from 1939 to 1991), and Founder of the South Hills Backyard Astronomers amateur astronomy club; permission granted for only non-profit use with credit to author.]

By Glenn A. Walsh

Reporting for SpaceWatchtower

Early Tuesday morning, Summer begins in the Northern Hemisphere of Earth, while at the same time, Winter begins in the Southern Hemisphere.

2022 Summer Solstice

For A.D. 2022, the season of Summer begins at Earth's Northern Hemisphere's Summer Solstice (and the season of Winter begins at the Southern Hemisphere's Winter Solstice) at the moment of the June Solstice: Tuesday Morning, 2022 June 21 at 5:14 a.m. Eastern Daylight Saving Time (EDT) / 9:14 Coordinated Universal Time (UTC – International time used by scientists; previously referred to as Greenwich Mean Time or Greenwich Civil Time). Summer will continue until the season of Autumn / Fall commences: Thursday Evening, 2022 September 22 at 9:04 p.m. EDT / September 23 at 1:04 UTC.

In Meteorology (Weather Science), the convention is to start a season on the first day of a calendar month. So, Meteorological Summer runs from June 1 to August 31.

In Etymology, the word Solstice comes from the Latin terms Sol (Sun) and Sistere (to stand still). In ancient times, Astronomers / Astrologers / Priests recognized that on one day of the year (in the Northern Hemisphere, on or near the day we now call June 21), the Sun would appear to stand-still as Sol reaches its highest point in the sky for the entire year. The motion of the Sun's apparent path in the sky (what is known astronomically, today, as the Sun's Declination) would cease on this day, before appearing to reverse direction.

Although the Summer months in the Northern Hemisphere are known for the year's warmest weather, the Earth is actually at the point in its orbit farthest from the Sun (astronomically known as the point of Aphelion) around July 5. The Earth's closest approach to the Sun (Perihelion) each year is around January 2. Hence, in general, the distance from the Earth to the Sun is not the major factor determining the heat of Summer or the cold of Winter.

This year, Earth Aphelion will occur on American Independence Day, Monday Morning, 2022 July 4 at 3:10 a.m. EDT / 7:10 UTC. At that moment, Earth will be the farthest from the Sun for the whole year: 94,509,598 statute miles / 152,098,454.4837 kilometers.

However, because Earth is farther from the Sun during our Spring and Summer seasons, people in Earth's Northern Hemisphere actually benefit from a few extra days of warmth (on average), than the number of days in the Autumn and Winter seasons of the year. When Earth is closer to the Sun, the Earth travels faster in its elliptical orbit around the Sun (during the Autumn and Winter months); and, when Earth is farther than average from the Sun (during the Spring and Summer seasons) the Earth travels a little more slowly --- again, this refers to the Northern Hemisphere. Hence, the Spring and Summer seasons, in the Northern Hemisphere, have a few more days than the Autumn and Winter seasons.

In fact, Jay Pasachoff, Field Memorial Professor of Astronomy at Williams College in Williamstown, Massachusetts and author of widely-used, college astronomy text-books, has precisely calculated the duration of each season, in the Northern Hemisphere:

* Summer: 93 days, 15 hours

* Spring: 92 days, 19 hours

* Autumn / Fall: 89 days, 20 hours

* Winter: 89 days, 0 hours

Solar radiation, and hence the heat from the Sun, depends on the length of daylight and the angle of the Sun above the horizon. The tilt of the planet's axis toward the Sun determines the additional and more direct solar radiation received by a planet's Northern or Southern Hemisphere, and hence, the warmer season of the respective hemisphere.

While the Sun does have motions (the Sun rotates on its own axis about once every 27 days; our Solar System revolves around the center of the Milky Way Galaxy once every 225 million-to-250 million Earth years), it is actually the motion of the Earth tilted on its axis, away from the plane of the ecliptic (Earth's orbital plane around the Sun), while revolving around the Sun, that causes the Earth's seasons.

As of this week in June, Earth's Axial Tilt, or Mean Obliquity is ~ 23.43636° or 23°26'10.8". The Mean Obliquity of Earth is ~ 0.00001°, or 0.04", less than 30 days ago.

Hence, as the Earth arrives at the point in its orbit around the Sun, when the north polar axis is most directly inclined toward the Sun, this marks the Summer Solstice in the Northern Hemisphere and the Winter Solstice in the Southern Hemisphere.

Alternately, the Winter Solstice in the Northern Hemisphere (the Winter Solstice is always on or near December 21) occurs when the Earth reaches the point in its orbit when the North Pole is most directly inclined away from the Sun. And, conversely, at this time Summer begins in the planet's Southern Hemisphere.

Currently (using a continuously updated formula), for Earth observers at precisely 23°26′10.9″ / 23.43637° North Latitude at the moment of the June Solstice, the Sun will appear to shine directly overhead. The line around the Earth at 23°26′10.9″ / 23.43637° North Latitude is known as the Tropic of Cancer (a.k.a. Northern Tropic). Likewise, at 23°26′10.9″ / 23.43637°) South Latitude is located the Tropic of Capricorn (a.k.a. Southern Tropic), where the Sun appears directly overhead at the moment of the December Solstice.

However, as the tilt of the Earth is dynamic, and changes minutely over the years, the location of the Tropic lines also change. Currently, these Tropic lines are moving north at the rate of 0.47 arc-seconds / 49.21 feet / 15 meters per year.

The names Tropic of Cancer and Tropic of Capricorn were coined in the last centuries B.C., when the Sun would appear in the Constellation Cancer the Crab on the June Solstice and in the Constellation Capricornus the Horned Goat on the December Solstice. However today, hours after the June Solstice, the Sun enters the Constellation Gemini the Twins, 30 degrees from Cancer. And at the December Solstice, the Sun is now in the Constellation Sagittarius the Archer.

This is due to “Precession of the Equinoxes” of Earth, which is analogous to the wobbling of a spinning top. In the case of the Earth, this 25,772-year wobble causes observers to view the Sun in different parts of the sky over the centuries, at the same time of year while remaining in the same geographical location. As the Earth wobbles over the centuries, the North Pole Star also changes. Currently, Polaris is our North Pole Star; around A.D. 13,700, Vega will be our North Pole Star, due to the Precession of the Equinoxes.

No matter which hemisphere, the day of the Summer Solstice always has the most hours and minutes of daylight (the length of time between Sunrise and Sunset) for the year, while the Winter Solstice always has the least number of hours and minutes of daylight for the year. The exact number of hours and minutes of daylight, for a particular location, depends on the locale's geographic Latitude on the Earth. Astronomers, amateur ("ham") radio operators, and long-distance radio enthusiasts (“radio DXers”), all of whom mostly depend on non-daylight hours to ply their craft, often prefer the days closer to the Winter Solstice.

The Vernal Equinox, when the season of Spring begins in the Northern Hemisphere (and the season of Autumn begins in the Southern Hemisphere), occurs between the Winter and Summer Solstices when the Earth reaches the point in its orbit around the Sun when the Earth's axis is inclined neither toward nor away from the Sun. Likewise, when the Earth reaches the point in its orbit around the Sun, between the Summer and Winter Solstices, when the Earth's axis is inclined neither toward nor away from the Sun, this is known as the Autumnal Equinox (beginning of Fall or Autumn) in the Northern Hemisphere; at this time Spring begins in the Southern Hemisphere. And, half-way between the beginning points of each season are Cross-Quarter Days, each related to traditional holidays: Groundhog Day (February 2), May Day (May 1), Lammas Day (traditionally, the first harvest festival of the year on August 1), and Halloween (October 31).

In ancient times, the Summer Solstice was known as Mid-Summer Day, in early calendars observed around June 24. At that time, May 1 to August 1 (i.e. the two Cross-Quarter Days) was considered the season of Summer. Such early European celebrations were pre-Christian in origin. Many will associate this ancient holiday with the famous William Shakespeare play, “A Midsummer Night's Dream.” Some speculate that the play was written for the Queen of England, to celebrate the Feast Day of Saint John.

As with the Roman Catholic Church's decision to Christianize the pagan Winter Solstice festivals with the introduction of Christmas Day on December 25 (by an early calendar, December 25 was reckoned as the Winter Solstice), the Church began to associate the Mid-Summer festivals with the Nativity of Saint John the Baptist on June 24. In the Christian Bible, the Gospel of Saint Luke implies that Saint John was born six months before the birth of Jesus, although no specific birth dates are given.

The most famous celebration of the Summer Solstice occurs each year at the Stonehenge pre-historic monument in England. Constructed between 3,000 B.C. and 1,600 B.C. in three phases, the actual purpose of the landmark is still unclear. However, it seems to have been associated with burials, originally. It was also used as a type of astronomical observatory, particularly for observing the Sun, which was important to help early cultures make annual decisions regarding agriculture.

Stonehenge is known as a way for pre-historic peoples to mark both the Summer and Winter Solstices. From inside the monument, a viewer facing northeast can watch the Sun rise (weather-permitting) above a stone outside the main circle of rocks, known as the Heel Stone, on the day of the Summer Solstice in the Northern Hemisphere. Although today, due to serious erosion of the stones, visitors on the Summer Solstice can only walk around the landmark from a short distance away during this annual event.

Although not as prominent as Stonehenge, a calendar ring using smaller rocks was also constructed at Nabta Playa in southern Egypt, perhaps as early as 7,000 years ago! As with Stonehenge, some stones aligned with Sunrise on the day of the Summer Solstice.

Today, a Stonehenge-like event occurs each year at the University of Wyoming (UW) Art Museum in Laramie, Wyoming, free-of-charge to the general public. At 12:00 Noon Mountain Daylight Saving Time (MDT) / 2:00 p.m. EDT / 18:00 UTC on the day of the Summer Solstice, visitors can see a single beam of sunlight shine through a solar tube in the ceiling of the UW Art Museum's Rotunda Gallery; the beam of sunlight then shines onto a 1923 Peace Silver Dollar embedded in the floor of the Museum's Rotunda Gallery. Visitors are encouraged to arrive at the museum by 11:30 a.m. MDT / 1:30 p.m. EDT / 17:30 UTC, to view this rather unique architectural feature.

The bright Star Spica (Alpha Virginis), the brightest star in the Constellation Virgo the Virgin and the 16^th brightest star in Earth's night sky (Apparent Visual Magnitude: + 0.97), may have helped develop another one of civilization's early calendars. A calendar of ancient Armenia used the year's first sighting of Spica in the dawn sky, a few days before the Summer Solstice, to mark the beginning of the New Year for this particular calendar. The development of this calendar somewhat coincided with the beginning of agriculture in Armenia.

Like clock-work, a well-known asterism (pattern of stars in the sky, not officially recognized as a constellation) of three stars shaped as a triangle is visible nearly overhead around local midnight during the Summer months (weather-permitting). And logically, as Star Trek's Mr. Spock might say, this asterism is known as the Summer Triangle!

Three of the brightest stars in the Summer sky constitute the Summer Triangle ---

Vega (Alpha Lyrae - brightest star in the Constellation Lyra the Harp); brightest of the three stars and closest to the zenith (highest point in the sky);
Altair (Alpha Aquilae - denotes the eagle eye and brightest star in the Constellation Aquila the Eagle); second brightest star of the trio;
Deneb (Alpha Cygni - denotes the tail star, is the brightest star in the Constellation Cygnus the Swan, and is the “head” star of the asterism known as the Northern Cross).

The term Summer Triangle was popularized in the 1950s by American author H.A. Rey and British astronomer Patrick Moore, although constellation guidebooks mention this triangle of stars as far back as 1913. And, during World War II, military navigators referred to this asterism as the “Navigator's Triangle.”

Regardless of city light pollution, the three bright stars of the Summer Triangle should be visible to nearly everyone in Earth's Northern Hemisphere (weather-permitting). So, just look overhead late-evening or early-morning throughout the Summer for these annual visitors to our Summer sky!

Internet Links to Additional Information ---

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeis

Sunday, 2022 June 19.

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

Monday, June 13, 2022

2024 Launch: NASA Mission to Jupiter Moon Europa

Image of the trailing hemisphere of Jupiter moon, Europa, in approximate natural color. This solid-state television image was taken by the NASA Galileo spacecraft during its second orbit around Jupiter on 1996 September 7. At the time, the probe was 417,900 statute miles / 677,000 kilometers from the ice-covered satellite. (Image Sources: NASA, Wikipedia.org, By NASA/JPL/DLR - Derivative of File:Europa-moon.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=74467836)

By Glenn A. Walsh

Reporting for SpaceWatchtower

While 2024 has been the targeted year for launch of Artemis and the return of astronauts to the Earth's Moon, NASA is also targeting a mission to another moon in 2024. The ice-covered moon of Jupiter, Europa, possibly with deep oceans, will be the first moon outside of the Earth-Moon system to receive a dedicated space probe.

This month, the main body of the space probe, known as the Europa Clipper, arrived at NASA's Jet Propulsion (JPL) in Pasadena, California. Now, JPL engineers and technicians will assemble the spacecraft and prepare it for launch.

The assembly will include installation of the nine science experiments on-board. Launch of the Europa Clipper is scheduled for October of 2024. The probe should arrive and enter an orbit of Jupiter in April of 2030.

“It’s an exciting time for the whole project team and a huge milestone,” said Jordan Evans, the mission’s project manager at JPL' as part of a NASA news release. “This delivery brings us one step closer to launch and the Europa Clipper science investigation.”

After entering orbit of Jupiter, Europa Clipper will conduct 44 fly-bys of Europa over a mission length expected to last 8 years.

Why not enter actual orbit of Europa, which is just a little smaller in size as the Earth’s Moon? Radiation emanating from the Jupiter magnetosphere at the orbit of Europa makes remaining this close to Jupiter dangerous for any spacecraft.

Europa's orbit lies completely within the harsh radiation fields of Jupiter. Even a hardened spacecraft, within such radiation fields, would last only a few months.

The problem is not the speed of scientific data accumulation. The scientific instruments can gather data pretty rapidly, so the limited life-span of the probe in Europa orbit would not have been a problem.

The problem comes when trying to communicate the data back to Earth. Because there are a limited number of receiving antennas on Earth, it takes longer to send the data back to NASA. Hence, the orbit of Europa will be elliptical, allowing the spacecraft to exist a fair amount of time beyond the radiation belts so it could survive for a longer period of time.

The Europa Clipper consists of an aluminum cylinder measuring 10 feet / 3 meters tall and 5 feet / 1.5 meters wide. This space probe will be launched a-top a SpaceX Falcon Heavy rocket.

Once the Europa Clipper gets to work in 2030, the probe will be looking to determine this moon's habitability. It will seek information on the atmosphere, surface, and interior of this small planetary body.

In particular, the probe will seek water plumes coming from fractures in the surface ice. It is estimated that water below the icy surface of Europa could exceed the amount of water in all of Earth's oceans, possibly by two times. Hence, scientists will be evaluating these water plumes to look for evidence of life in the ocean of Europa.

The Europa Clipper is named after 3-masted, ocean merchant vessels of the 19^th century.

Europa was one of the first four non-Earth moons discovered, following the invention of the astronomical telescope. Famous Italian astronomer Galileo Galilei discovered Europa with his telescope on 1610 January 8. Europa was one of the four moons he found orbiting Jupiter that evening, including the natural satellites Io, Callisto, and Ganymede; these are known as the Galilean moons.

Europa is the smallest of the four Galilean satellites, and the 6^th closest to Jupiter of the 80 known Jupiter moons. Europa is also the 6^th largest moon in our Solar System.

The name Europa is taken from the name of the daughter of Tyre, a Phoenician noble-woman of Greek mythology; all four Galilean satellites are named after a lover of Zeus, the Greek counterpart of Jupiter

Internet links to additional information ---

NASA/ JPL News Release on Europa Clipper: Link >>> https://www.jpl.nasa.gov/news/nasas-europa-clipper-mission-completes-main-body-of-the-spacecraft

Europa Clipper -

Link 1 >>> https://www.nasa.gov/europa

Link 2 >>> https://en.wikipedia.org/wiki/Europa_Clipper

Europa >>> https://en.wikipedia.org/wiki/Europa_(moon)

Galilean Satellites: Link >>> https://en.wikipedia.org/wiki/Galilean_moons

Galileo Galilei: Link >>> https://en.wikipedia.org/wiki/Galileo_Galilei

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeis

Monday, 2022 June 13.