Celestial Seasonings – October 2019

By Heather Durham | September 30, 2019

This month offers an almost nightly schedule of celestial events, the majority of which are viewable with the naked eye. There is quite a plethora to view. As well, we will enjoy the full Hunter’s Moon (the first Moon after the Harvest Moon). Happy birthday to NASA!

Meteor showers take their names from the constellation or comet in the portion of the sky in which they appear. For instance, the Draconids appear near the constellation Draco, the Perseids appear near the constellation Perseus, the Taurids appear near the constellation Taurus, etc.


October 1

Happy birthday NASA…..which turns 61 today!

The Moon is at its closest to the Sun today as well (Space.com, 2019; Seasky.org, 2019).

October 2

There will be a Change of Command ceremony at the International Space Station. Luca Parmitano from the European Space Agency will replace Russian Cosmonaut Alexsey Ovchinin.

M31 (the Andromeda galaxy) may be viewed with binoculars. (It is also known as NGC 224).

October 3

There will be conjunction of the Moon and Jupiter, when the waxing crescent Moon will pass by less than 2 degrees to the north of Jupiter in the evening sky.

The planet Mercury, will be at its furthest point from the sun. Around 18:39 EDT, from Milton, they both should be visible.

October 5

There will be a conjunction of the Moon and Saturn, during which time the Moon will pass less than a degree to the south of Saturn. The two of them may be visible in the evening sky.

NGC 300, which is a spiral galaxy in the Sculptor constellation, is located where it can be observed above our southern horizon.

October 6

Today, the October Camelopardalid meteor shower reaches its peak.

October 8

Draconids Meteor Shower. This minor shower that produces about 10 meteors per hour will peak this year on October 8. Viewing will be the best in the evening or most likely around midnight as it follows the setting of the first quarter Moon which will set by then. These meteors will appear anywhere in the sky. From Milton, the shower will display directly above the horizon and will be active throughout the night.

October 9

A bright Mercury will be well placed in the evening sky.

 October 10

The Moon reaches its furthest place from the Sun.

The peak of the Southern Taurid meteor shower occurs on this date. From Milton, however, it won’t be visible before 18:56 pm EDT each night. Look towards the eastern horizon.

October 15

M33 from the Triangulum Galaxy is viewable. (It is also known as NGC 598).

October 19

Mercury will be shining bright.

October 20

Mercury at Greatest Eastern Elongation. This planet reaches elongation of 24.6 degrees from the sun and can be viewed low in the western sky just after sunset (Seasky.org, 2019).

October 21-22

Orionids Meteor Shower. This shower, an average one, can display up to 20 meteors per hour when at its peak. These dust grains from Halley’s comet will peak on the night of the 21st and morning of the 22nd. The Orionids tend to be bright even though the second quarter Moon will block some of the ones furthest away. View from a dark sky just after midnight. The best and brightest displays will occur near 05:00 AM EDT..

October 24

The peak of the Leonids meteor shower occurs on this date. The best display is said to be just before dawn.

October 26

There will be a conjunction of Mars and the Moon.

The western half of NGC 869 in the constellation Perseus may be viewable around midnight in or near Milton.

October 27

Uranus at Opposition. At times between 19:35 and 5:16, it should become visible from Milton.

October 29

There will be a conjunction of the Moon and Mercury, as well as one of the Moon and Venus.

The face of this blue-green planet will be fully lit by the sun. It should be visible all night long but is best viewed by telescope.

October 31

There will be a conjunction of the Moon and Jupiter. Look to see the Moon go by approximately one degree north of Jupiter in the evening sky.


Previous in sequence: Celestial Seasonings – September 2019; next in sequence: Celestial Seasonings – November 2019


References:

In-the-sky.org. (2019, September). Guides to the Night Sky. Retrieved from  https://in-the-sky.org/search.php

Seasky.org. (2019, September). Astronomy Reference Guide. Retrieved from http://www.seasky.org/astronomy/astronomy.html

Space.com. (2019, September). Space Launch Calendar 2019: Sky Events, Missions & More. Retrieved from https://www.space.com/32286-space-calendar.html

Wikipedia. (2019, September 22). Alexsey Ovchinin. Retrieved from en.wikipedia.org/wiki/Aleksey_Ovchinin

Wikipedia. (2019, September 25). Andromeda Galaxy. Retrieved from en.wikipedia.org/wiki/Andromeda_Galaxy

Wikipedia. (2019, September 17). Conjunction (Astronomy). Retrieved from en.wikipedia.org/wiki/Conjunction_(astronomy)

Wikipedia. (2019, September 19).Draconids. Retrieved from en.wikipedia.org/wiki/Draconids

Wikipedia. (2019, September 22). Leonids. Retrieved from en.wikipedia.org/wiki/Leonids

Wikipedia. (2019, September 22). Luca Parmitano. Retrieved from en.wikipedia.org/wiki/Luca_Parmitano

Wikipedia. (2019, September 21). Messier Object. Retrieved from en.wikipedia.org/wiki/Messier_object

Wikipedia. (2019, May 28). New General Catalogue. Retrieved from en.wikipedia.org/wiki/New_General_Catalogue

Wikipedia. (2019, August 14). NGC 300. Retrieved from en.wikipedia.org/wiki/NGC_300

Wikipedia. (2018, August 16). NGC 869. Retrieved from en.wikipedia.org/wiki/NGC_869

Wikipedia. (2019, June 9). Opposition (Astronomy). Retrieved from en.wikipedia.org/wiki/Opposition_(astronomy)

Wikipedia. (2019,September 30). Orionids. Retrieved from en.wikipedia.org/wiki/Orionids

Wikipeida. (2019, September 24). Perseids. Retrieved from en.wikipedia.org/wiki/Perseids

Wikipedia. (2019, September 26). Sculptor (Constellation). Retrieved from en.wikipedia.org/wiki/Sculptor_(constellation)

Wikipedia. (2019, September 28). Taurids. Retrieved from en.wikipedia.org/wiki/Taurids

Wikipedia. (2019, September 23). Triangulum Galaxy. Retrieved from en.wikipedia.org/wiki/Triangulum_Galaxy

Celestial Seasonings – September 2019

By Heather Durham | August 30, 2019

We will have the pleasure to see this month in our night sky, weather permitting, several wonderful celestial events. These include the usual sweep of stars and constellations, but also glimpses of galaxies, planets, comets, changes of moon phase, and the Fall equinox. Enjoy.

September 3

Mercury at superior solar conjunction

This elusive planet will pass very closely to the sun. It is often lost in the suns glare. This marks the end of Mercury‘s apparition in the morning sky and its transition to becoming an evening object over the next few weeks. It will also pass apogee at a distance of 1.37 AU from Earth making it appear very small and distant. (in-the-sky.org, 2019).

September 4

C2018 W2 (Africano) at perihelion

This comet will make its closest approach to the sun and might be visible from Rochester in the morning sky at 20:59 when it rises 21 degrees above the northeastern horizon. While this is not expected to be seen with the naked eye, it might be visible with bird-watching binoculars.

September 8

Conjunction of the Moon and Saturn

The Moon will be 11 days old when the moon and Saturn share the same right ascension. The two objects or make a close approach around the same time. From Rochester, they will be visible in the evening sky at about 8:09 PM. They will continue to be observable until around 2am when they sink below 8° above your southwestern sky.

Close approach of the Moon and Pluto

When the moon is 10 days old the pair can be seen in the evening sky at around 7:25 pm. They should be visible with binoculars.

September 23

September equinox

No matter where you live on Earth, the sun will rise almost due east and set almost due west on this, the Equinox of this coming season. The timing of this event will be 3:36 EDT. The sun has a right ascension of approximately equal to 12 hours.

September is a month for new beginnings. The days will be shorter and the nights longer until the December Solstice.

In Rochester, the astronomical twilight begins at 4:57 am, the sunrise at 6:32 am, then the astronomical twilight ends at 8:14 pm. Sunrise is at 6:32 am, sunset at 6:39 pm and the time at which the sun is at its highest point in the sky is at 12:36 pm.

September 24

Close approach of the Moon and M44

When the moon is 25 days old, the Moon and the beehive cluster, M44 will make a close approach of each other. The pair will be visible and the dawn sky rising at 1:49 AM and reaching an altitude of 45° above the eastern horizon before disappearing from view as dawn breaks. The pair may be visible using a pair of binoculars.

Moon Phases, September 2019, Rochester, New Hampshire

Moon Phase – Date – Time of Day

  • First Quarter – September 5 – 11:11 PM
  • Full Moon. – September 14 – 12:35 AM
  • Last Quarter – September 21 – 10.43 PM
  • New Moon – September 28 – 2:27 PM

Previous in sequence: Celestial Seasonings – August 2019; next in sequence: Celestial Seasonings – October 2019


References:

Dominic Ford, Editor. (August 11, 2019). From the Inner Planets Feed. Retrieved from
in-the-sky.org/news

Equinox NH 2019 Celebration. (August 2019). Equinox New Hampshire. Retrieved from www.equinoxnh.com

Skymaps.com Monthly Report, (August 2019). Monthly Map. Retrieved from www.skymaps.com/downloads.html

timeanddate.com. (August 2019). September Equinox. Retrieved from www.timeanddate.com/calendar/september-equinox.html

Wikipedia. (August 2019). Conjunctions. Retrieved from en.m.wikipedia.org/wiki/Conjunction_(astronomy)

Wikipedia. (August 2019). M44. Retrieved from en.m.wikipedia.org/wiki/Beehive_Cluster

Wikipedia. (August, 2019). September 2019 Equinox. Retrieved from en.m.wikipedia.org/wiki/September_equinox

 

Celestial Seasonings – August 2019

By Heather Durham | July 31, 2019

Fiftieth Anniversary of Apollo 11 – Just Past

For the first time in human history, man landed on the moon on Sunday, July 20, 1969. Michael Collins remained in moon orbit with the command module, while two others descended to the surface in the lunar module. Edwin E. “Buzz” Aldrin served as the lunar module pilot of Apollo 11.

Apollo 11 launched from the Kennedy Space Center at 9:32 am on July 16, 1969.

It took 2 years to locate the appropriate location for landing. Neil Armstrong was the first to set foot on the lunar surface, followed 19 minutes later by Aldrin.

These men located and brought back to Earth, 47.5 pounds of lunar material. The astronauts returned on July 24, 1969, after spending 8 days in space.

There were and are many celebrations for this 50th anniversary. This past January, the U.S. Mint released a 50th anniversary coin.

August 1 – New Moon

The new moon begins a two-week waxing (or increasing) phase that culminates in the full moon. Once visible, this would be a superb time to view other celestial events because the waxing crescent is visible in the evening sky.

August 8 – Venus at Perihelion

During which Venus is at its closest approach to the sun, a distance is 107,477,000 km. (66,783,111 miles).

August 9 – Mercury at Greatest Western Elongation

Mercury reaches elongation at 18.3 degrees from the sun. It might be viewed at dawn depending upon the weather conditions at that time.

August 12, 13 – Perseid Meteor Shower

The Perseid Meteor showers come from a debris stream that surrounds the 133-year orbit of the Swift-Tuttle comet. Beginning in 1865, a young filament from the stream gives a mini peak display before the maximum shower occurred. At peak, meteor rates may reach 60 or more per hour.

These particles slam into Earth’s atmosphere so fast that it doesn’t take a large particle to put on quite a fantastic show. Actually the meteors are no bigger than a grain of sand or a pea. The show is produced by the kinetic energy that changes to heat caused by friction in the upper atmosphere,

Although these may not be that prolific this August due to the full moon, there should be 10-15 meteors per hour … a substantially lesser amount that in other years like 2016.

This month’s shower should be at its strongest right after the comet passes along the portion of its orbit that meets the Earth’s orbit as well as after it passes near the sun.

August 14 – Venus at Superior Solar Conjunction

While not visible with the Sun in the sky, Venus may be seen passing through the evening sky.

August 15 – Full Moon

August 30 – New Moon

Having two new moons in the same calendar month happens only once in every two to three years. (New moons are not lit, so there is nothing lunar to see).


References:

Lewin, Sarah. (2019, January 8). Perseid Meteor Shower 2019: When, Where & How to See It. Retrieved from www.space.com/32868-perseid-meteor-shower-guide.html

Powell, Martin J. (2019). Mercury. Retrieved from www.nakedeyeplanets.com

Sky & Telescope. (2019). Meteor Showers. Retrieved from www.skyandtelescope.com

Wikipedia. (2019, July 30). Apollo 11. Retrieved from en.wikipedia.org/wiki/Apollo_11

Wikipedia. (2019, July 27). Moon. Retrieved from en.wikipedia.org/wiki/Moon

Wikipedia. (2019, March 11). Perseids. Retrieved from en.wikipedia.org/wiki/Perseids

 

Skies over Milton, May Edition

By Peter Forrester | May 9, 2019

Greetings, stargazers, wherever you may be! Apologies for the long delay in writing this update – I have been dealing with some personal issues which took up a great deal of my time every day, for about the last month, but that has now been resolved.

So here are your skywatching tips for this “Merry Month of May”!

Past events (included only for completeness, except for the meteor shower which is ongoing):

Thursday, May 2: Moon near Venus, morning sky at 11:00 AM (Eastern Daylight Time)

Friday, May 3: Moon near Mercury, morning sky at 6:00 AM.

Saturday, May 4: New Moon at 6:46 PM.

Monday, May 6: Three events: Moon near Pleiades (open cluster) at 1:00 AM.

Also, the peak of the Eta Aquariid meteor shower occurred at 10:00 am (most visible for a 7-day period around this peak, still visible now just above the horizon before dawn). This meteor shower is formed by debris that separated from Halley’s Comet hundreds of years ago. Easier to see in the Tropics and in the Southern Hemisphere. The shower lasts until Tuesday, the 28th of May.

Third, the Moon was near the bright star Aldebaran at 6 PM.

Tuesday, May 7: The Moon was near Mars at 9:00 PM.

Future events: 

Thursday, May 9: The Moon will be near the bright star Pollux (one of the bright ones in Gemini) at 11:00 PM.

Saturday, May 11: First Quarter Moon at 9:12 PM.

Monday, May 13: Moon will be at perigee (closest to Earth in the current orbital period) at 5:54 PM.

Saturday, May 18: Full Moon at 5:10 PM.

Tuesday, May 21: Mercury will be at superior conjunction (meaning it is directly behind the Sun) with the Sun at 9:00 AM. After this it will pass into the evening sky.

Wednesday, May 22: Moon will be near Saturn at 4:00 PM. People in South Africa will be able to see an “occultation”, meaning that Saturn will be behind the Moon.

Sunday, May 26: Moon at apogee (furthest from the Earth) at 9:00 AM. Also, Last Quarter Moon at 12:33 PM.

Tuesday, May 28: Ceres will be at opposition at 6:00 PM. This means that it is in a straight line with the Earth and Sun, with the Earth in the middle. This is when it is brightest, but at apparent magnitude of 6.7, it is still too dim to see with the naked eye unless you have extremely dark skies.

Ceres is the largest object in the Main Asteroid belt between Mars and Jupiter, and the only “dwarf planet” there. It was the first asteroid to be discovered, way back in 1801. The NASA spacecraft Dawn orbited Ceres from 2015 to 2018, see the reference below for more information on this fascinating space body.

For more skywatching events (including some in the free download PDF that involve the Moon being near various objects which I omitted), or to see the events in Universal Time or ones that are not visible from my location in Milton, New Hampshire, see http://Skymaps.com/skycalendar/.


Previous in series: Skies Over Milton, April Edition


References:

Thalassoudis, Kym. (2000-19). Skymaps. Retrieved May 9, 2019 from skymaps.com.

Wikipedia. (2019, May 8). Ceres (dwarf planet). Retrieved from https://en.wikipedia.org/wiki/Ceres_(dwarf_planet).

Wikipedia. (2019, April 20). Conjunction (astronomy)#Superior and inferior. Retrieved from https://en.wikipedia.org/wiki/Conjunction_(astronomy)#Superior_and_inferior

Wikipedia. (2019, May 4). Eta Aquariids. Retrieved from https://en.wikipedia.org/wiki/Eta_Aquariids.

Wikipedia. (2019, May 8). Opposition (astronomy). Retrieved from https://en.wikipedia.org/wiki/Opposition_(astronomy).

Circumpolar Constellations: Ursa Major

By Peter Forrester | April 18, 2019

Greetings all! Let’s talk about one of the best-known group of stars (not a constellation) in the sky.

Yes, I mean the Big Dipper, which is referred to as an “asterism,” or a collection or shape of stars that are not recognized as a constellation (the 88 “official” ones were defined in 1928, at a meeting of the International Astronomical Union, which just celebrated its 100-year anniversary a few days ago).

Officially, by the way, a constellation is a region in the sky, not just a set of bright stars that form a shape but everything around them as well. For instance, when the Sun, Moon, or a planet is in the same direction as a constellation we say that it is “in” that constellation. The same is true of comets, asteroids, nebulas, quasars, pulsars, black holes, whole galaxies, or even dust. Every point in the sky is defined as belonging to one or more constellations (the “more” being along the borders).

But back to the asterism known as the Big Dipper. In this case, the 7 stars that make up the Dipper (called the Plough in the U.K.) are part of the constellation Ursa Major (the Great Bear).

I have not covered the Big Dipper until now because as of a few months ago, it was still very low to the horizon in the early evening, and thus not very visible if you have any kind of treeline.

Six of the seven stars in the Dipper are of 2nd degree magnitude, and the other one is 3rd degree. They are the brightest stars in Ursa Major.

Many of my readers will already know that the Big Dipper, as I said about Orion, can be used to find other stars and constellations easily. Tracing the side of the bowl upward, the line extends to Polaris, the North Star, which is part of the constellation called Ursa Minor. This is very useful for nighttime navigation without a compass, as Polaris is always located to the north. Sailors have been using the stars to find their direction for millennia, and the Big Dipper was what they used to locate Polaris, since Polaris is only 3rd degree and looks similar to every other star of the same color and brightness.

Using the same two stars that form a line to Polaris, tracing the line in the opposite direction brings you to another bright constellation, one of the Zodiac: Leo the Lion, whose shape resembles a rectangle that touches a backwards question mark. Thirdly, following the curve of the handle brings you to the constellations Bootes (resembling a kite, its brightest star called Arcturus) and Virgo (brightest star Spica). Hence the once-popular saying “Arc to Arcturus, and spike to Spica”). There are some other lesser known direction-finding lines using different stars in the Big Dipper, see the Big Dipper reference below if you want to know more about this.

Ursa Major is very close to the north celestial pole, and thus as explained previously, it  is circumpolar. Therefore, meaning it never sets from the sky when seen from northern latitudes such as the United States or Europe, but appears to go in a circle every 24 hours around Polaris, the star located directly over the North Pole of Earth.

Incidentally, the Big Dipper has been considered as the tail of a bear, and various other images (this one makes no sense because bears don’t have long tails). The rest of the bear consists of dimmer stars to the right of and below the bowl when it is lying flat on its bottom (the bowl to the right of the handle – it is close to the horizon when it is in this direction).

In popular culture, the Big Dipper is found on the flag of the state of Alaska, and a few other flags and coats of arms. It may even be mentioned in the Bible (its reference in the book of Job is disputed by scholars).

I once made a scale-model view of the distance of the stars in the Big Dipper, a side-view, if you will. One of the stars was so much further than the rest that I had to mount it on a separate piece of cardboard from the rest. This was a school project, and unfortunately I no longer have it. But it is interesting to note that the shapes we see are only from our perspective, and most constellations would appear very different in other solar systems.

I’m going to leave the discussion there, because I’m feeling a bit under the weather, but I wish you all the best time while skywatching, and be sure to look up when you go out!


Previous in series: Circumpolar Constellations: Cassiopeia


References:

Wikipedia. (2019, March 10). Asterism (astronomy). Retrieved from https://en.wikipedia.org/wiki/Asterism_(astronomy).

Wikipedia. (2019, April 2). Big Dipper. Retrieved from https://en.wikipedia.org/wiki/Big_Dipper.

Wikipedia. (2019, April 1). Constellation. Retrieved from https://en.wikipedia.org/wiki/Constellation.

Wikipedia. (2019, March 29). Ursa Major. Retrieved from https://en.wikipedia.org/wiki/Ursa_Major.

Skies Over Milton, April Edition

By Peter Forrester | April 2, 2019

Greetings on this fine sunny day! (I wish I could call it “warm”!)

Here are your monthly skywatching events, including one that already occurred. Note: all times are in US Eastern Daylight Savings Time (EDT) unless otherwise noted, which is 4 hours less than Universal Time (UT). Note: not all of these events occur at a time where the sky in Milton will be dark enough to see them.

Tuesday, April 2: Moon near Venus, 3:00 am EDT. Also Moon near Mercury, 10:00 PM.

Friday, April 5: New Moon at 4:51 AM. This is the start of “Lunation 1191” (a lunation is about 29.53 days, or the time between one new moon and the next. The exact length of a lunation varies a little bit, see the reference on “New moon” for more information).

Monday, April 8: Moon near the Pleiades at 7 pm.

Tuesday, April 9: Moon near Mars at 6 am (evening sky). Moon near Aldebaran (brightest star in constellation Taurus) at noon (in evening sky).

Friday, April 12: First Quarter Moon at 3:05 PM.

Sunday, April 14: Mars near Aldebaran at 9 pm.

Friday, April 19: Full Moon at 7:11 AM.

Monday, April 22, Lyrid Meteor Shower peaks at 8 pm. It is visible from the 14th to the 30th. 10 – 20 fast, bright meteors per hour during the peak, unfortunately the Moon’s brightness well make these meteors harder to see. The meteors can be seen all over the sky, but the radiant (point of origin) is between the constellations Lyra and Hercules.

Tuesday, April 23: Moon near Jupiter, 9:00 AM.

Thursday, April 25: Moon near Saturn at 9:00 AM (occultation, which means the nearer object passing in front of the other and therefore blocking light from it, will occur. In this case, the occultation will only be visible in parts of Australia, New Zealand, and South America).

Friday, April 26: Last Quarter Moon at 6:18 PM.

For more of these events, or to check out other skywatching tips, be sure to visit skymaps.com.

Until my next, enjoy the skies, and this glorious spring which is now upon us (at least in the Northern Hemisphere)!


Previous in series: Skies Over Milton, March Edition


References:

Thalassoudis, Kym. (2000-19). Skymaps. Retrieved April 2, 2019 from skymaps.com.

Wikipedia. (2019, March 25). Lyrids. Retrieved from https://en.wikipedia.org/wiki/Lyrids.

Wikipedia. (2019, January 10). New moon. Retrieved from https://en.wikipedia.org/wiki/New_moon.

Wikipedia. (2019, March 10). Occultation. Retrieved from https://en.wikipedia.org/wiki/Occultation.

More Facts About Jupiter

By Peter Forrester | March 29, 2019

I previously wrote about observation of the planet Jupiter. I thought as a bonus, some of you might like to read some more about the fifth planet from the Sun.

Jupiter is the largest of the eight planets in our Solar System. It is named after the king of the gods in Roman mythology. It is made up mostly of gases, and has a prominent storm called the Great Red Spot that has persisted for hundreds of years and is bigger than the Earth. But everyone knows these facts, right? What about some facts about the Red-spot planet that you might not know about?

Some other interesting facts about the largest planet:

Jupiter is mostly made of the lightest element, hydrogen, although about 25% of its mass is helium, the second element (only about 10% of the molecules).

The first spacecraft to fly near Jupiter was called Pioneer 10, in 1973. Pioneer 11 then flew even closer in 1974, followed by the Voyager 1 and 2, both of which flew further away in 1979 but used its gravity to speed them up on the way to the more distant planets.

Jupiter is currently being orbited by a space orbiter called Juno, which entered into orbit in 2016 and will continue until 2021, when it will be intentionally steered into the planet’s outer gas layers (to protect the moons from a collision).

This is the second spaceship to orbit the king of the planets – the previous one, Galileo, orbited from 1995 to 2003, and is named after the Italian astronomer Galileo Galilei, who improved on a recent (1608) invention: the refracting telescope, and is one of the first people known to have used it for astronomy.

Through his telescope in January 1610 he discovered the four largest moons of Jupiter, the first group of objects ever to be discovered that were definitely orbiting an object other than the Sun or Earth. The discovery of the Galilean moons provided evidence to Galileo that all objects in the solar system do not orbit the Earth (this evidence spelled the doom of the Geocentric model of the solar system, although it took a while for the theory to be fully abandoned by scientists). I will let you read for yourself of the religious controversy this caused, which led to Galilei being obliged to recant any belief that the Earth is not the center of the universe, and also spending the end of his life under house arrest.

For a long time Galileo was credited as the sole discoverer of these moons, and hence they are called the Galilean moons after him (though they were also independently discovered by Simon Marius in Germany, a month or two before that, who proposed their individual names when he published his findings in 1614). Galileo also made the first telescopic observations of several other amazing things: craters on the Earth’s Moon, analysis of sunspots, and the phases of Venus, though the telescope only magnified 30 times, much less than the powerful ones used now. He also may have seen the planet Uranus in 1612 (discovered to be a planet in 1781), and also wrote on physics and engineering.

The Galilean moons are called Callisto, Ganymede, Europa, and Io (all named after mythological lovers of the god Jupiter). Ganymede is the largest moon and 9th largest object in the Solar System, being larger than the planet Mercury. It is also the largest object in the Solar System that does not have a substantial atmosphere. Three of the four moons are larger than our Moon (all except Europa). All four are also rounded by their own weight unlike the smaller ones, and hence would be considered “dwarf planets” if they orbited the Sun.

The space mission called Galileo made some amazing discoveries, mostly about Jupiter and its moons. For example, it discovered evidence of a liquid ocean under the surface of the moon Europa, now widely considered to be the most likely place in the solar system, outside of Earth, for life to still exist (though it is likely it once existed on Mars). It also found evidence to explain the origins of Jupiter’s thin rings (much less visible than Saturn’s famous ones).

On its way to Jupiter, the probe also observed the collision of comet fragments into Jupiter in 1994 (the first impacts were not visible from Earth), as well as discovering the first known asteroid-moon system in 1993.

Speaking of moons, there are now 79 known moons of Jupiter with stable orbits, the most satellites discovered around a single object to date other than the Sun. The four Galilean ones are much bigger than all the rest of Jupiter’s moons. No more moons for Jupiter were discovered until 1892. This moon, Amalthea’s largest dimension of 250 km is less than one tenth the diameter of Europa, the smallest of the Galilean moons. Amalthea was the last planetary moon to be discovered by direct visual observation.

If Jupiter was 75 times more massive, it would be capable of nuclear fusion and be considered a star, and give off light. However, if it got just a little more massive than it is now, it is thought that it would start shrinking and become denser (in other words, its radius would actually decrease). However, it gives off more heat than it receives from the Sun, and actually does shrink by about 2 cm per year. Jupiter has 2 and a half times the mass of the other 7 planets combined. Its mass is often used as a comparison when talking about extrasolar planets that have been discovered.

It is theorized but unknown whether Jupiter has a solid core.

Jupiter could fit 10 times across the diameter of the Sun.

Every 398 days Earth overtakes Jupiter in its orbit, and then it appears to move backwards for a few days.

Jupiter rotates about every 10 hours (the fastest of any planet in the Solar System). The cloud layers at the poles orbit at a different rate than those at the equator of Jupiter, about 5 minutes longer, although the planet’s official rotation rate is based on measurements of its magnetosphere by radio waves.

I could go on and on, but you can all read as much of this as you want over on Wikipedia or Google other sources. Until next time, adieu!


References:

Wikipedia. (2019, March 15).  Comet Shoemaker-Levy 9. Retrieved from https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9 .

Wikipedia. (2019, March 13). Galileo (spacecraft). Retrieved from https://en.wikipedia.org/wiki/Galileo_(spacecraft).

Wikipedia. (2019, March 18). Galileo Galilei. Retrieved from https://en.wikipedia.org/wiki/Galileo_Galilei.

Wikipedia. (2019, March 22). Juno (spacecraft). Retrieved from https://en.wikipedia.org/wiki/Juno_(spacecraft).

Wikipedia. (2019, March 26). Jupiter. Retrieved from https://en.wikipedia.org/wiki/Jupiter.