Eris: Plutoid, Dwarf Planet, or 10th Planet?

Eris was discovered on January 5, 2005 by Michael E. Brown, Chad Trujillo, and David A. Rabinowitz. Its orbit is more eccentric and more highly inclined than Pluto’s, and it is almost as large as Pluto, having a diameter that is 97.9% that of Pluto. Eris last came to perihelion on July 23, 1699 when it was in the constellation Virgo shining at a magnitude of 14.8, well beyond the reach of any telescopes existing at the time.

Pluto, Eris, and Satellites – Sizes and Orbital Distances to Scale

Eris has an orbit that is so eccentric (e = 0.44) that it actually spends some time each orbit closer to the Sun than Pluto is during the outer reaches of its orbit. Pluto’s aphelion distance is 49.31 AU, and Eris will be closer to the Sun than that for 99 years, from 2208 to 2307.

Eris is closer to the Sun than Pluto’s average distance of 40.70 AU for 43 years, between 2236 and 2279. Eris again reaches perihelion in 2257, when it will be 38.09 AU from the Sun.

Eris has an orbit that is tilted at nearly a 45° angle with respect to the ecliptic. This takes it through some interesting constellations during its 559-year orbital period. Here is its upcoming travel itinerary.

Upcoming Travel Plans for Eris (not subject to change1)

2022   Cetus
2036   Pisces
2059   Cetus
2064   Aries
2126   Perseus
2174   Camelopardalis
2197   Lynx
2208   Ursa Major
2237   Canes Venatici
2245   Coma Berenices
2256   Virgo
2274   Libra
2281   Hydra
2285   Centaurus
2286   Lupus
2298   Norma
2308   Ara
2320   Pavo
2357   Indus
2367   Tucana
2376   Grus
2399   Phoenix
2434   Sculptor
2487   Cetus

1 Unless the constellation boundaries are redrawn due to precession or other considerations

In Greek & Roman mythology, Eris is the goddess of strife and discord. 500 years hence, in 2522, Eris will once again be in Cetus, as it is today. But where will we be? What kind of life will our great-great-great-great great-great-great-great-great-great-great-great-great great-great grandchildren have in 2522? Here are some of my hopes for 2522.

  • Humanism will have replaced religion.
  • There will be no poverty in the world.
  • Everyone will have adequate health care, and it will be free.
  • Zero population growth will have been achieved by the only humane way possible: having fewer children.
  • There will be no more wars, no weapons of mass destruction.
  • There will be no need for guns, and no one will have them.
  • Violence will not be tolerated, nor will society glorify it or dwell on it in any way.
  • Individuals who “cross the line” and violate others through the use of physical violence will be psychologically re-engineered so they will live productive and fulfilling lives without being a threat to others. This neutralization of violent tendencies must be accomplished humanely and in a way that does not violate the individual’s essential humanity.
  • The Earth will be treated as the oasis it is.
  • Money will no longer exist, nor will it be needed.

Though no one alive today is likely to ever see any of these things, that in no way excuses us from working substantially towards these goals. To do anything less is a dereliction of moral duty.

Non-Profit Mail Overload

I receive enough solicitations in the mail from non-profit organizations to fill a 10-ream paper box every couple of months. I don’t think I have ever seen it this bad. I know that needs are great and worthwhile causes many, but giving $25 to an organization supporting cause xyz should not result in a dozen other organizations supporting similar causes mailing me multiple times each year.

There has to be a better way. Catalog companies had to solve this problem decades ago because of the expense of printing and mailing catalogs to existing and prospective customers. You mail your best customers often, those who don’t spend much or purchase infrequently less often, and prospective customers maybe once in a great while.

If the U.S. Postal Service continues to have financial problems, one source of revenue would be to increase the non-profit postage rate, and that would force many non-profit organizations to use a more sophisticated approach for their mailings.

Why not start now? I’d like to see a non-profit organization established whose sole purpose is to help other non-profit organizations to mail donors and prospective donors efficiently. Let’s give it a placeholder name: Nonprofit Mailing Association (NMA). Each participating non-profit organization would confidentially provide their donor lists and contribution history for each donor to NMA, and NMA in turn would use the data received from your organization and other non-profit organizations to rank-order donors based on likelihood to contribute and amount likely to contribute.

In the marketing business, this process is called “modeling”. Each model needs to take into consideration the amount you give (are you a $25 or $500 donor?), the frequency you give (monthly, 2-3 times a year, annually, or every couple of years or so), and to which non-profits. Other behaviors need to be taken into account. Does the donor tend to support organizations that they seek out directly, or are they more likely to respond to prospect mailings?

This modeling will result in fewer mailings but a lower acquisition cost per donor. From a donor standpoint, hopefully this will stop frequent mailings to individuals who have never donated to an organization. Once a year is often enough. Anything more borders on harassment. Besides, is the average person more likely to look at a non-profit mailing if they receive one in the mail on average each day or ten?

This approach should also apply to political organizations.

Using a more sophisticated approach to non-profit mailings will result in lower mailing and printing costs for the non-profit, and less printed material ending up in the recycling stream or—more often—the landfill.

A Case for Ten Planets

Clyde Tombaugh (1906-1997) spent the first fifteen years of his life on a farm near Streator, Illinois, and then his family moved to a farm near Burdett, Kansas (no wonder he got interested in astronomy!), and he went to high school there. Then, on February 18, 1930, Tombaugh, a self-taught amateur astronomer and telescope maker, discovered the ninth planet in our solar system, Pluto. It had been nearly 84 years since the eighth planet, Neptune, had been discovered, in 1846. And it would be another 62 years before another trans-Neptunian object (TNO) would be discovered.

Clyde Tombaugh made his discovery using a 13-inch f/5.3 photographic refractor at the Lowell Observatory in Flagstaff, Arizona.

Clyde Tombaugh was 24 years old when he discovered Pluto. He died in 1997 at the age of 90 (almost 91). I was very fortunate to meet Prof. Tombaugh at a lecture he gave at Iowa State University in 1990. At that lecture, he told a fascinating story about the discovery of Pluto, and I remember well his comment that he felt certain that no “tenth planet” larger than Pluto exists in our solar system, because of the thorough searches he and others had done since his discovery of Pluto. But, those searches were done before the CCD revolution, and just two years later, the first TNO outside the Pluto-Charon system, 15760 Albion (1992 QB1), would be discovered by David Jewitt (1958-) and Jane Luu (1963-), although only 1/9th the size of Pluto.

Pluto is, by far, the smallest of the nine planets. At only 2,377 km across, Pluto is only 2/3 the size of our Moon! Pluto has a large moon called Charon (pronounced SHAR-on) that is 1,212 km across (over half the size of Pluto), discovered in 1978 by James Christy (1938-). Two additional moons were discovered using the Hubble Space Telescope (HST) in 2005: Hydra (50.9 × 36.1 × 30.9 km) and Nix (49.8 × 33.2 × 31.1 km). A fourth moon was discovered using HST in 2011: Kerberos (10 × 9 × 9 km). And a fifth moon, again using HST, in 2012: Styx (16 × 9 × 8 km).

Pluto has been visited by a single spacecraft. New Horizons passed 12,472 km from Pluto and 28,858 km from Charon on July 14, 2015. Then, about 3½ years later, New Horizons passed 3,538 km from 486958 Arrokoth, on January 1, 2019.

Only one other TNO comparable in size to Pluto (or larger) is known to exist. 136199 Eris and its moon Dysnomia were discovered in 2005 by Mike Brown (1965-), Chad Trujillo (1973-), and David Rabinowitz (1960-). It is currently estimated that Eris is 97.9% the size of Pluto. Not surprisingly, in 2006 Pluto was “demoted” by the IAU from planethood to dwarf planet status. (Is not a “dwarf planet” a planet? Confusing…)

My take on this is that Pluto should be considered a planet along with Eris, of course. The definition of “planet” is really rather arbitrary, so given that Pluto was discovered 75 years before Eris, and 62 years before TNO #2, I think we should (in deference to the memory of Mr. Tombaugh, mostly) define a planet as any non-satellite object orbiting the Sun that is around the size of Pluto or larger. So, by my definition, there are currently ten known planets in our solar system. Is that really too many to keep track of?

There is precedent for including history in scientific naming decisions. William Herschel (1738-1822) is thought to have coined the term “planetary nebula” in the 1780s, and though we now know they have nothing to do with planets (unless their morphology is affected by orbiting planets), we still use the term “planetary nebula” to describe them today.

In the table below, you will find the eight “classical” planets, plus the five largest TNOs, all listed in order of descending size. (The largest asteroid, Ceres, is 939 km across, and is thus smaller than the smallest of these TNOs.)

You’ll see that the next largest TNO after Eris is Haumea, and that its diameter is only 67% that of Eris.

I’ve also listed the largest satellite for each of these objects. Venus and Mercury do not have a satellite—at least not at the present time.

It is amazing to note that both Ganymede and Titan are larger than the planet Mercury! And Ganymede, Titan, the Moon, and Triton are all larger than Pluto.

Largest Objects in the Solar System

Object Diameter (km) Largest Satellite Diameter (km) Size Ratio
Jupiter 139,822 Ganymede 5,268 3.8%
Saturn 116,464 Titan 5,149 4.4%
Uranus 50,724 Titania 1,577 3.1%
Neptune 49,244 Triton 2,707 5.5%
Earth 12,742 Moon 3,475 27.3%
Venus 12,104 N/A N/A N/A
Mars 6,779 Phobos 23 0.3%
Mercury 4,879 N/A N/A N/A
Pluto 2,377 Charon 1,212 51.0%
Eris 2,326 Dysnomia 700 30.1%
Haumea 1,560 Hiʻiaka 320 20.5%
Makemake 1,430 S/2015 (136472) 175 12.2%
Gonggong 1,230 Xiangliu 200 16.3%

Should any other non-satellite objects with a diameter of at least 2,000 km be discovered in our solar system, I think we should call them planets, too.

A Smarter TV

It seems to me that so-called “Smart TVs” just give you more of the same: corporately-curated, pay-to-subscribe, advertising-supported television.

I’d like to be able to create my own “channels” from websites and services that I choose. My channels would include:

  • PBS Passport
  • Curiosity Stream

Currently, I access these by selecting the content I want on a laptop computer which I’ve connected to my television.

It would be nice to have the web browser built into the television and a TV remote that includes a keyboard (real or virtual) and a touchpad (or arrow keys) to navigate website menus and enter text into search boxes. That way you could dispense with the connected laptop.

It would also be nice to be able to automatically and securely log in to each website by simply clicking on the channel icon. No apps to download, configure, or install.

Does such a television even exist?

Election Day Eclipse

The second of two total lunar eclipses this year visible from Tucson will occur early next Tuesday morning, November 8. Yes, this is Election Day in the U.S. Having a total lunar eclipse on Election Day is so rare that it has never happened before since the United States was founded in 1776. Whether or not our nation survives its current paroxysms, we can rest assured that lunar eclipses will continue to occur as they have for billions of years.

Here are the local circumstances for Tucson, Arizona.

Time (MST)EventAltitude
1:02 a.m.Penumbral Eclipse Begins69˚
~1:45 a.m.Penumbra First Visible?62˚
2:09 a.m.Partial Eclipse Begins57°
3:16 a.m.Total Eclipse Begins44°
3:59 a.m.Greatest Eclipse35°
4:42 a.m.Total Eclipse Ends26°
5:23 a.m.Astronomical Twilight Begins18°
5:49 a.m.Partial Eclipse Ends13°
5:52 a.m.Nautical Twilight Begins12°

There are few astronomical events as impressive as a total lunar eclipse, and we’ll have a front-row seat Election Day morning.

Every month, the full moon passes close to the Earth’s shadow, but because of the Moon’s tilted orbit it usually passes above or below the shadow cone of the Earth. This month is different!

Tuesday morning, the Moon orbits right through the Earth’s shadow. At 1:02 a.m., the Moon dips his proverbial toe into the Earth’s shadow, when the Moon is 69˚ above Tucson’s SW horizon. This is the undetectable beginning of the eclipse, when the leading edge of the eastward orbiting-Moon “sees” a partial solar eclipse. When no part of the Moon sees anything more than the Earth blocking some but not all of the Sun, we call that a penumbral eclipse. The very subtle penumbral shading may just begin to be detectable around 1:45 a.m.

When the partial eclipse begins at 2:09 a.m., the upper left edge becomes the first part of the Moon to “see” a total solar eclipse. In other words, from part of the Moon now, the Earth totally eclipses the Sun.

Totality begins at 3:16 a.m. when all of the Moon sees the Earth completely blocking the Sun. Mid-totality occurs at 3:59 a.m., when the center of the Moon is closest to the center of the Earth’s shadow. At that moment, the Moon’s coppery color should be darkest.

That color is caused by sunlight refracting (bending) through the Earth’s atmosphere and shining on the Moon even though from the Moon the Earth is completely blocking the disk of the Sun. The reddish or orangish color imparted to the Moon during totality is the combined light of all the world’s sunrises and sunsets. What a beautiful thought! Had the Earth no atmosphere, the Moon would utterly disappear from view during totality—the time it is completely within the Earth’s umbral shadow.

Totality ends at 4:42 a.m., and the partial eclipse ends at 5:49 a.m. during morning twilight. When the last vestiges of partial solar eclipse leave the Moon at 6:56 a.m., the (penumbral) eclipse ends at moonset as the Sun is rising in the ESE.

This leisurely event can be enjoyed with the unaided eye, binoculars, a telescope, or all three. Don’t let anyone in the family miss seeing it!

The next total eclipse will not grace our skies until March 13, 2025.

If you haven’t already done so, please be sure to vote! It is your responsibility that comes with the privileges of your living in these United States. And voting should only be the beginning of your civic involvement. The quality of our government and elected representatives is directly proportional to the sum total of our collective civic involvement. And that has been pretty poor in recent years. Unlike an eclipse, democracy is not a spectator sport!