A perfect two for one post – yoga astrology and autumnal equinox – a super combination!
Tomorrow marks the Autumnal Equinox – when days and nights become equal for a brief period before the nights grow longer. It is also the phase of Libra, the bringer of balance and equality (certainly, something we can all use in the wind swept days of fall).
The element air is definitely integral to this sign of Libra. As the winds of change mark the season, the scales analyze the direction and balance the flow. No conflicts are involved – the emissary Libra acts in harmony to make the necessary changes.
As Libra governs the lower back, these yogis require stability to avoid injuring this vulnerable area of the body. Poses that bring strength, balance and a sense of center are what this sign needs to stay confident and strong.
Begin with Table Balance 
and find your center as you extend one arm along with the opposite leg. Be sure to keep your alignment and stay connected to your center.
Another powerful pose to strengthen and balance the back and front body is
Virabhadrasana III or Warrior III.
Setu Bandha Sarvangasana builds stability in the lower back. 
Start easy with supine cat-cow and slowly build to the traditional bridge pose over time. This one can be done supported with a block holding the body at the level of the sacrum.
Finally, a supreme balancer is the pranayama technique Nadi Shodhana. It promotes a clear channel for the mind to make decisions and think objectively.
When you need more encouragement, reflect on this all encompassing quote by Gary Kraftsow:
A Yoga PrayerMay my physical body have strength, stability, and structural integrity,May my vital body have health, vitality, stamina, and immunity.
May my intellect be clear, capable, curious, eager, and open.
May my character have faith, wisdom, compassion, humility, integrity and patience.
May my emotions be stable and joyful.
May my heart be open.
May I be totally integrated structurally, physiologically, intellectually, psychologically, emotionally, and spiritually.
Photos taken from Yoga Journal