Connecting the Dots

Four planets line up outside my bedroom window just before sunrise today (April 29).

The planets and the sun seem to lie on a single straight line. While it may seem like a lucky shot, this alignment is anything but momentary. 

Non-coincidence

Stellarium view of sky without horizon at the time and place

The line joining the dots marks the ecliptic - the edge-on view of the orbital plane of the earth along which the sun appears to move during its daily motion. All other planets in our solar system also orbit the sun more or less on the same plane. Seen from this edge-on perspective, ALL the planets are on that line ALL the time.   

The rarity is seeing four or more of the planets visible without being washed out by the sun and above horizon. At the moment this picture was taken, the missing members of this family portrait, Mercury, Uranus and Neptune are also on an imaginary extension of the same line, hidden below the horizon.  The image on the right is a snapshot from Stellarium showing the full solar system at the time from my location, without the horizon in the way. 

Circumstellar

Source: Wikipedia

Rewind time by about five billion years at the time of the birth of the sun (4.5 billion by more precise estimates through computer simulation and nucleocosmochronology).

A dark giant molecular cloud made of mostly hydrogen and helium swirl in place of our solar system. A part of it collapses under gravity to form the proto sun. As gravity attracts more mass the pressure triggers nuclear fusion at the core and ignites it into a star. Sunlight shines for the first time in our solar system. 

There are no planets around the newborn sun, yet. In their place there is the residual circumstellar matter which flattens out into the shape of a disc. Over the next 100 million years or so, gravity will cause this material to clump in places forming the cores of planets, planetesimals, asteroids and other bodies in the solar system. This line is the center line of the protoplanetary disc seen edge-on.

Conjunction

The brightest to the naked eye, this morning as always, was Venus. While it is four hundred million miles away from Jupiter "as the crow flies", the two appear very close from our vantage point. They will appear within half a degree of each other as seen from the earth the following day April 30. This is the Jupiter-Venus conjunction of 2022. 

Differential Reality

Like with all astronomical objects the view is a glimpse into the past and a differentially deferred reality.  Light having a finite speed takes time to cover astronomical distances. The closest objects are Venus and the sun  - each over 90 million miles. The light from them takes a little over 8 minutes to reach us. 

At nearly a billion miles from us, Saturn is the farthest of the four in this image. The light from it is nearly 90 minutes old when it reaches us. If we could watch a soccer match start on Saturn, the game would nearly be over locally by the time we did. A well understood phenomenon. Yet something I find quite amazing in how it defies common sense.

The sky is always telling us fascinating stories. Only if we are willing to connect the dots.