Sagittarius Time Machine

The bright stars that outline our constellations beckon to us from a remarkably wide range of distances. Many of these stars are super-luminous giant stars and hot blue dwarf stars. More typical stars like our Sun—and the even more abundant red dwarf stars—are much too faint to see with our unaided eyes, unless they are only a few light years away. Thus many of the stars we see when we look up at the night sky are the intrinsically brightest ones, the “whales among the fishes.”

Trigonometric parallax directly provides us with the best estimate of the distance to each of these stars (provided they are not more than a few hundred light years away), and once you know the distance, it is easy to calculate when the light you are seeing tonight left each one of them. It is enjoyable to contemplate what was going on in Earth history when each star’s light began its long journey across interstellar space, the tiniest fraction of which is reaching your eyes as you look up on a clear night.

This article is the next in a series featuring the major stars of a prominent constellation. We turn now towards Sagittarius, which is currently crossing the celestial meridian at the end of evening twilight.

Below you will find a chart showing the constellation Sagittarius and the bright stars that define its outline. The official IAU-approved star names are listed, where available, or the Bayer designation. There’s a printer-friendly PDF version of this chart at the bottom of this article. There’s room for you to write in the year when the light we are currently receiving left the photosphere of each star, using the provided table (which is updated automatically to today’s date).

The “Teapot” asterism of Sagittarius

The table below contains all the relevant information. There are three tabs: Parallax, Distance, and Time. The first three columns of each tab show the star name, the Bayer designation, and the spectral type and luminosity class listed in SIMBAD.

On the Parallax tab, the parallax in millarcseconds (mas) is listed in column D, along with the uncertainty in the parallax in column E, and the year the parallax was published in column F. All are from SIMBAD. I will update these values as new results become available, but please post a comment here if you find anything that is not current, or is incorrect.

On the Distance tab, the parallax and parallax uncertainty for each star is used to calculate the range of possible distances to the star (in light years) in columns D through F. The nominal value given in column E is our current “best guess” for the distance to the star.

On the Time tab, the range of distances from the Distance tab are used to determine the range of years when the light we are seeing at this point in time would have left the star. The earliest year (given the uncertainty in parallax) is shown in column D, the most likely year in column E, and the latest year (given the uncertainty in parallax) in column F.

Here’s a printer-friendly PDF version of the Sagittarius chart where after printing you can enter the nominal year from column E of the Time tab next to the name for each star. The year values on the Time tab will update automatically to reference the current date.

Interest Connect

Make a list of your interests, either mentally or on paper. Are you curious about who else living in your area shares an interest with you? Wouldn’t it be nice if there were a safe online platform that would provide you with email addresses of others in your area who have a mutual interest so that you could exchange private emails? This might lead to a productive email exchange, meeting in person, forming an advocacy group, or working on a special project together. Two people or several. Your choice. And no advertising or marketing! I don’t think anything like this exists yet. Here’s my vision.

The name of the online platform will be Interest Connect.

A management organization (an independent non-profit entity or benefit corporation) will create and manage Interest Connect.

Each member will have a profile on the service that contains only the following basic information, viewable in its entirety only by the member and the management organization.

  • Your name (real name, no aliases)
  • Your email address
  • Your geographic region
  • Your interests

The list of geographic regions will be created and maintained by the management organization. The list will include the names of metro areas, subregions of metro areas, cities, towns, counties, and so on. Members can always ask for a new geographic region to be added. A member can only belong to one geographic region and will have no visibility into the other regions. There could, however, be visibility into levels of the same geographic region. For example: NW Tucson, Tucson, Pima County. Each member must provide proof of residency in their chosen geographic region by sharing their residential address with the management organization. That address will be independently verified, kept confidential, and will never be made public.

The management organization approves interest types and adds them to the list that members can select to add to their profile. There will be a large number of interests to choose from, and members can always ask for new ones to be added.

Some interests will be general, and others highly specialized.

Interest Connect is not a public discussion group, but a group to foster person-to-person private communication.  More than two members with the same interest could certainly arrange to communicate collectively amongst themselves via email.

As a member of Interest Connect, what would you see? You would see the names and email addresses of others in your geographic region that share the same interest as you.

Safety from predators is crucial, and the management organization will have complete authority to remove anyone from membership in Interest Connect that violates their terms and code of conduct.

Here’s a simplistic example showing four hypothetical individuals in the same geographic region. Interests A, B, C, D, E, F, and G are simply placeholders in our example for the actual interests that would be listed in Interest Connect.

Each member has a private profile that looks like this…

Marija Kelemen
mkeleme@gmail.com
Tucson, AZ
Interests: Interest A, Interest B, Interest C

Nikolaos Hubbard
nikhubb2@icloud.com
Tucson, AZ
Interests: Interest D, Interest E, Interest F

Slavica Brankovič
slavica2933@aol.com
Tucson, AZ
Interests: Interest B, Interest D

Aidan Storstrand
aidan.storstrand@outlook.com
Tucson, AZ
Interests: Interest B, Interest D, Interest G

Each member would have visibility into other members like this…

Marija would see the following:

Interest B
Slavica Brankovič: slavica2933@aol.com
Aidan Storstrand: aidan.storstrand@outlook.com


Nikolaos would see the following:

Interest D
Slavica Brankovič: slavica2933@aol.com
Aidan Storstrand: aidan.storstrand@outlook.com


Slavica would see the following:

Interest B
Marija Kelemen: mkeleme@gmail.com
Aidan Storstrand aidan.storstrand@outlook.com

Interest D
Nikolaos Hubbard: nikhubb2@icloud.com
Aidan Storstrand: aidan.storstrand@outlook.com


Aidan would see the following:

Interest B
Marija Kelemen: mkeleme@gmail.com
Slavica Brankovič: slavica2933@aol.com

Interest D
Nikolaos Hubbard: nikhubb2@icloud.com
Slavica Brankovič: slavica2933@aol.com


Each member’s interest lists will be dynamic, so that interests can be added or removed at any time. Perhaps notifications could be set up (optionally) so that if someone new adds one of your interests, you will automatically be notified.

How to fund this noble endeavor without resorting to hosting irritating advertising? Each member would pay a modest annual membership fee. No mandatory automatic renewals, please!

What do you think? Has something like Interest Connect already been done somewhere? Do you have suggestions or concerns? I would be interested in hearing your thoughts. Feel free to post a comment here.