<Hipparcos is providing us with a wealth of data and especially some explanation about our own Sun's whereabouts within the Milky Way!
In the october issue of Ciel et Espace, there's a fascinating article about our Sun's extraordinary voyage.
Our sun is surrounded by stars that are on average younger than 60 million year old. Better yet: those stars ar all daughters of the same history, and our Sun is the sole intruder! Our sun is much much older (4.5 Billion years old.
The galaxy is like a ballroom with dancers waltzing around it; most with partners; our Sun, dancing alone or changing from one partner to the next:-(. It takes 250Million years to turn once around the Galaxy and we go above and below the galactic plane, in a sinusoidal way, but we also encounter clouds of matter. A fortysome stars, in constellations such as the Big Dipper, Canis major, Pegasus, Cancer, Cetus, all follow the same path across the galaxy. This is a stellar flow younger tha 500 million years old and we have been within it for the past 100 million years. A stellar belt, called the Gould Belt, inclined 18 degrees relative to the galactic plane, including the Hyades and the Pleiades, is expanding. It's our stellar province, but only for a while.
We crossed it's border, 20 million years ago. The sun describes epicycles in its path across the Milky Way, enounters giant clouds, makes a few steps with them and changes partners.
500 Million years ago, we came under the influence of the so-called Supercloud (including other clouds such as the Hyades cluster, Praesepe, Capella, Cor Caroli, Vindemiatrix. A stellar nursery starts and forms Sirius and its sisters (500 stars in total). Half of it wouldl form the actual Big Dipper flow. 200 million years ago, another burnout formed the Castor flow and Vega and Fomalhaut. 100 Million years ago, the Supercloud encoutered the Carina Spiral Arm, which flattened it and disrupted it on its periphery. A new disc plane is created(where Deneb came from). 70 Million years ago, after crossing the spiral arm, that supercloud's internal regions began expanding and formed a gas ring, called the Lindblad ring. A first generation of stars appeared (the Pleiades flow and the Cassiopeia-Taurus association). Its members occupy a huge portion of the sky, today: the historic heart of our sky is: Segin, Cih (Cassiopeia), Dzeta Tauri, Alkaid (Ursa Major), Epsilon Persei, Delta Ceti, the Pleiades, M34, NGC2516. The Gould Belt got its actual characterisitcs 40 million years ago. This belt has provoked a surge of supernovae, hence a number of pulsars found in the belt. 20 million years ago, a huge firework welcomed the solar system when we came into the belt. The door from which we came inside the belt is in near Canis Major (the Canis tunnel), an abnormally empty zone. It could be the vacuum left by the supercloud.
The exit door is in the direction of Hercules and in several million years, our sun will have left the Supercloud, only to meet another cloud and flirt with other suns.
It helps to know where you are when you see those stars.

Raoul