Hard aspects by transit Saturn can definitely be a challenge. They're probably second in line to hard transit Pluto aspects. Saturn is the teacher and disciplinarian, and doesn't want to make it easy!
An aspect is when two bodies are at certain distances from one another in the Zodiac. The Zodiac is made up of 12 signs, and each sign is 30 degrees, so there are 360 degrees total. Some aspects are major, and they have the strongest impact, and of the major aspects, 3 can be considered hard by Saturn: conjunction, square, and opposition.
Conjunctions occur when they're in the same location in the Zodiac. They are neutral aspects that amplify energy. When transit Saturn is conjunct one of your natal planets, this can amplify the restrictive. limiting nature of Saturn on whatever that planets rules, and it can be very difficult.
Squares occur when they're 90 degrees, or 3 full signs, apart. They are aspects of internalized friction, and with transit Saturn, they can *really* turn up the challenges you have with yourself internally.
Oppositions occur when they're exactly opposite one another in the Zodiac. They are aspects of external friction, and with transit Saturn, difficulties may seem out of your control to some degree, and more flexibility is needed.
As for the personal planets, they are the Sun, Moon, Mercury, Venus, and Mars (well technically the Sun and Moon are luminaries and Mercury, Venus, and Mars are the personal planets, but they tend to be lumped together and are for this post).
Saturn is the planet of restriction, demanding lessons be learned first, and this is most present under a hard aspect by Saturn to your personal planets. You absolutely must do things the right way (Saturn's way), and learn your lessons, otherwise Saturn continues to squeeze you.
Make sure you're signed up for the monthly worksheet if you want to keep track of the transit planets like Saturn every month!
Surviving Hard Aspects to the Personal Planets by Transit Saturn:
Transit Saturn to Natal Sun
With the natal Sun ruling the self, transit Saturn conjunct, square, or opposite can make you feel extra restricted overall in your life. It may be difficult for you to pursue what you want, and you may have extra responsibilities. It can feel like everything falls on you, and you can be easily overwhelmed and pessimistic.
How to survive:
You really need to do things Saturn's way, and be as responsible, ethical, and smart as possible. You likely have to work harder than you have before, but it can lead to good things once this passes. Basically, just keep moving forward doing things the right way, and for the right reasons. Look around at what you may need to learn, and don't be stubborn and refuse to learn it. Remind yourself of the good little things in your life to manage the pessimism.
All of this can be most focused on the areas of life ruled by the house your natal Sun rules (the house with Leo on the cusp).
Transit Saturn to Natal Moon
With the natal Moon ruling your emotions, transit Saturn conjunct, square, or opposite can make it difficult for you to express what you're feeling openly or properly, and you may avoid emotions as much as possible. You may have trouble getting your emotional needs met, or feeling supported. You can experience developments that make you feel more insecure and unstable.
How to survive:
Saturn to your natal Moon is likely trying to get you to focus on old emotional issues that you've avoided and lessons you haven't learned. Saturn wants you to be logical and objective about it, hence being more cut off emotionally, but you can learn how to properly express what you feel and manage your emotions in a healthy way. If you feel unsupported, you likely need a new support system with better people.
All of this can be most focused on the areas of life ruled by the house your natal Moon rules (the house with Cancer on the cusp).
Transit Saturn to Natal Mercury
With natal Mercury ruling your mind, transit Saturn conjunct, square, or opposite can make it difficult for you to express your thoughts, ideas, and opinions. You may be quieter and keep more to yourself, worried about what other people will say or think. You can be more down in the dumps, a little too realistic.
How to survive:
If you're keeping a lot to yourself, there is likely an issue that needs to be worked on that is blocking you, or a lesson that needs to be learned about proper expression. You may need to learn to be more confident in your ideas and thoughts, and worry less about what others think. Try to focus on the big picture so you don't get lost in the challenging details.
All of this can be most focused on the areas of life ruled by the houses your natal Mercury rules (the houses with Gemini and Virgo on the cusp).
Transit Saturn to Natal Venus
With natal Venus ruling your relationships, transit Saturn conjunct, square, or opposite can make you feel more limited in your relationships. You may see people leave your life, or you walk away from others. You may take on more responsibilities in relationships that stick around, and this can cause issues. Existing issues in your relationships can be exposed, and it can be a make-or-break moment.
How to survive:
First, you have to either work on issues in existing relationships, or walk away from them. It needs to either get better, or end. That's kind of it with Saturn. People who leave your life likely weren't very good for you anyway, though it may not feel like that in the moment. Focus on what a healthy relationship is and means to you, what your wants and needs are in relationships, and how you can both be a better partner with others, and attract better partners for you. Saturn only wants you to have positive, enriching, supportive relationships, so it's time to work on that.
All of this can be most focused on the areas of life ruled by the houses your natal Venus rules (the houses with Taurus and Libra on the cusp).
Transit Saturn to Natal Mars
With natal Mars ruling your energy and drive, transit Saturn conjunct, square, or opposite can zap your energy. You can find it difficult to be motivated to get anything done, and it may seem like when you do get moving, everything takes so much longer. It can take a while for you to take initiative with anything, if you even do.
How to survive:
Saturn may be focusing on a few different things for you. If you struggle with taking initiative normally, then Saturn may be trying to get you to develop better confidence in yourself to do that. If you struggle with motivation normally, then Saturn may be trying to bring attention to what drives you and inspires you to take action so it's not only healthier, but also something you can tap into whenever you need it. And if your energy is zapped, Saturn is likely trying to get you to take a break because you've been pushing yourself too hard.
All of this can be most focused on the areas of life ruled by the house your natal Mars rules (the house with Aries on the cusp).
Suggested Reading: The Survival Series: How to survive transit Pluto, Neptune, Uranus, Saturn, Full Moons, and Mercury retrograde in the houses, and Hard Pluto to the Personal Planets